I’m honoured to have been asked to present this year’s annual lecture for the Planning Officers’ Society, on 15 April at De Morgan House, 57-58 Russell Square, London, WC1B 4HS.
I’ll be presenting RCKa’s recent research into suburban intensification, including our MHCLG-funded PropTech research into the housing capacity of London’s small sites, our work on the London Plan Small Sites Design Code, and the potential of repurposed golf courses to help deliver new homes and social infrastructure.
London’s suburbs, which Sir John Betjeman famously called “the home of the gnome” half a century ago, have become the hunting ground of the SUV. These hulking death machines dominate the streets and their presence is a blight on our neighbourhoods.
This is not something we collectively agreed to; it’s the product of personal choice, inadequate regulation and cheap finance.
In 1973 the poet laureate was conflicted in his disdain for the loss of the countryside to suburban expansion, while also celebrating the value of the commonplace to the “ordinary citizen”. Betjeman could never have anticipated the arrival of the Personal Contract Purchase.
The argument goes that car ownership is a manifestation of personal freedom, yet this liberty is desperately dull. Fully 70% of private vehicles sold in 2024 were grey, white, black or silver.
One by one, the streets become increasingly achromatic: white cars, white homes – the coral bleaching of our towns and cities
We see the same in our houses too: the depressing prevalence of house-flipping, where developers buy up characterful but shabby properties and expunge any remnants of joy by wrapping them in clinical white insulated render, and swap timber sash windows with anthracite grey aluminium. One by one, the streets become increasingly achromatic: white cars, white homes – the coral bleaching of our towns and cities.
Some of this is driven by sales conventions: grey windows shift more easily than green. Part L requires a new thermal envelope and crisp white render is an easy sell. Increasingly prescriptive space standards demand a precise number of rooms of a particular size, and build costs make it impossible to provide any more than the bare minimum. Like pebbles in the ocean, the churning of the regulatory tide softens every hard edge into vapid uniformity.
Last week a draft replacement National Planning Policy Framework (NPPF) appeared, correctly diagnosing that the simple division between major and minor applications with a threshold of 10 homes was anachronous. A new category – medium – is proposed, capturing schemes with 10 or more dwellings, but fewer than 50, with an accompanying reduction in the burden on applicants and a scheme of delegation to elude incalcitrant planning committees. This is welcome, but also a missed opportunity to add a further category covering single family homes.
Since its introduction in 2012, the NPPF has included a specific allowance for single houses in rural areas that are “truly outstanding” where they would otherwise be refused. Oligarchs, hedge fund managers and wealthy actor types are well-served, all able to afford the world’s most talented designers (or the most expensive planning lawyers) to smooth the path to constructing gaudy palazzi or sleek modernist mansions in the countryside. The new NPPF retains it.
It is not right that there is no equivalent provision for urban areas, precisely where we should be encouraging new homes to be built. A new category of development application is needed which enables individuals or families to buy up scraps of land and transform them into homes that respond to their individual needs and personal tastes.
Maintaining the alliterative terminology, the introduction of a new micro classification for new houses should remove all of the conventional planning requirements and impose just dimensional parameters to ensure limited impact on neighbours: no taller than the highest point of an immediate neighbour, perhaps; no closer to the road than the front face of an adjoining property; remaining outside a 45-degree angle drawn from the primary window serving an existing habitable room.
In line with the requirement to make the best use of land, this should impose a maximum site size of, say, 200sqm, but beyond that the Building Regulations would be enough to ensure that the dwelling is safe, secure, well ventilated, warm, sustainable and accessible.
As for space standards? Forget them. Japan has demonstrated how a talented architect can squeeze exquisite homes from the most preposterous of plots when freed from the constraints of a suite of housing standards that assume every family unit falls neatly into normative expectations.
Automatic permission, even within spatial constraints, would inevitably lead to some localised horrors, but the upside would be a parallel wave of surprise and joy sprinkled across the suburbs
Not everyone adheres to the conventions expected of them by government decree, nor does everyone desire to live in a standard home. Extended and non-nuclear families are poorly catered for by the NDSS, and the demographic target for a two-bed, four-person flat is surely so niche that their prevalence speaks more to our failure to build proper homes than it reflects a genuine need.
A micro planning category, freeing individual houses from the constraints of the planning system, save from the obvious safeguards needed to protect the amenity of immediate neighbours and important heritage, would – at the very least – allow families to build the homes they really need. Within conservation areas, new development must “preserve” or “enhance”. It follows that, outside of them, character should be free to evolve and adapt.
“In-keeping”, “subservient” and “sympathetic” are the last refuge of the chronically unimaginative. Let’s excise them from the lexicon.
For sure, automatic permission, even within spatial constraints, would inevitably lead to some localised horrors, but the upside would be a parallel wave of surprise and joy sprinkled across the suburbs. And, let’s be honest – can we really claim that the current planning system is effective at preventing the most egregious designs? At best, it drives us inexorably towards housing homogeneity.
It is time to loosen up. As Hannes Coudenys, founder of Ugly Belgian Houses, a website dedicated to poking gentle fun at the peculiar aesthetic choices of Flemish self-builders, said: “It’s better to be ugly than to be boring.” Who are we to argue?
In May this year, the government launched a consultation on the potential sub-division of planning application categories. Up to now, full planning applications fell into one of two classifications: minor, and major, with the threshold for those schemes falling into one or the other being the net addition of 10 homes. Any less than this, you’d be a minor application; any more, a major—regardless of whether this involved the creation of 10 homes or 1,000. This has consequences in the level of information required to validate the application and the time taken to determine it: minor applications should receive an outcome in no more than eight weeks from the point of validation, but for major schemes this rises to 13 (although very few applications are ever actually determined within this period).
The proposed bands retain the minor category at between 1 and 9 inclusive, but introduces a new medium definition of between 10 and 49 homes, with the major classification now including those schemes yielding more than 50 dwellings.
This makes a lot of sense, although perhaps it doesn’t go far enough. Applications for 50 homes should not be treated in the same way as those for 500, so there should be a further division of the major application type, probably around the 250-home mark.
But what about at the smaller scale? SME developers are likely to be the ones building the majority of homes within the minor category, but community builders, councils and housing associations also have a part to play. But what about those new homes for private clients; the boutique developers who have managed to acquire a tiny scrap of land in a fashionable area, or the families who want to carve out a sliver of their back garden in order to build a home for their kids? Single family homes are an opportunity for creativity and innovation, as well as being a vital tool in our attempt to intensify our towns and cities. Many well-known architects have cut their teeth on crafty infill projects that squeeze delightful and spacious homes on the most constrained urban sites.
He Lives in a House, a Very Big House
The National Planning Policy Framework (NPPF) has, for some time, included a clause which allows new homes to be built in the countryside provided that certain criteria are met. The most recent iteration of the NPPF encapsulates this objective in paragraph 84, which states that “…decisions should avoid the development of isolated homes in the countryside unless one or more of the following circumstances apply:”
e) the design is of exceptional quality, in that it: i. is truly outstanding, reflecting the highest standards in architecture, and would help to raise standards of design more generally in rural areas; and ii. would significantly enhance its immediate setting, and be sensitive to the defining characteristics of the local area.
Extract from paragraph 84, National Planning Policy Framework, December 2025
This is great for wealthy actors, hedge fund managers and oligarchs, but why should they have all the fun?
I think it’s time to introduce a similar policy to allow the development of single homes in urban areas, free from the many restrictive planning constraints which consistently make small-scale development costly and unpredictable. In keeping with the alliterative minor/medium/major naming convention, we need a new category: micro.
Micro Scope
Here’s my proposal:
Within urban and suburban areas, but outside conservation areas and not within the curtilage of a statutorily listed building, it should be possible to build a new house with automatic planning permission, provided that the external volume of the house fits within a set of maximum parameters determined by the outlook of neighbouring windows and private amenity space. Applications must demonstrate only how they respond to a) flood risk, b) highways and transport requirements, c) waste and recycling provision, and d) risk of contamination.
The dimensional parameters might include the following limitations:
The development must comprise a single dwellinghouse on a plot no larger than 200sqm;
The development volume must be no taller than the highest part of an immediate neighbour;
The development volume must be no closer to the highway than the principal elevation of an immediate neighbour;
The development volume must not extend beyond a 45% line drawn in a horizontal plane from the nearest jamb of any primary window serving any habitable room;
The new dwelling must be no closer to the site boundary than the neighbouring dwelling is;
The distance between the principal window serving a habitable room in the new development must be no closer than 16m from that of a principal window serving a habitable room within a neighbouring dwellinghouse.
This is how these policies might appear in three dimensions, using a street infill site type:
View from streetView from rear
External appearance should be entirely down to the applicant: local character does not have to be “adhered to” or “respected”. I have no say in the colour or model of the car my neighbour chooses to park outside the front of their house; nor should they have a say in what I want my home to look like.
Building Regulations compliance is distinct from planning, so each home delivered this way will need to confirm to minimum levels of structural integrity and feature basic amenities, such as a toilet. It’s unlikely a mortgage lender is going to let self-builders create anything too outlandish.
Beyond these constraints, there should be no requirement to adhere to local planning policies, including space standards. You want to create a voluminous home consisting of a single room? No problem.
Not every site will allow a house to be built using these parameters, but then there’s always the normal planning route to fall back on.
Be Careful What You Wish For
Of course, there’s a risk that such a permissive policy could result in some dreadful interventions, but on the other hand, it could also unleash a wave of creative and extraordinary homes to meet a range of different needs. And can we really say that the planning policies of the last century has allowed only buildings of exceptional quality to be built? I don’t think so.
Existing planning policies are necessarily prescriptive to ensure that rogue developers don’t throw together exploitative shoeboxes that can’t meet the basic standards necessary for a comfortable existence, but these requirements also assume that everyone neatly slots into a conventional family unit. What about the extended multi-generational families; co-habiting friends happy to share a living room, but not a bathroom; or the retired couple who don’t need the space afforded by their large family home, but who have a lifetime of possessions that can’t be squeezed into a one-bed flat?
Giving almost complete flexibility to design an entirely bespoke houses—free from planning conventions and context—would allow families to create homes to suit their specific needs, and encourage architects to come up with innovative ways to craft extraordinary homes from the most unlikely of plots: witness the brilliance of the Japanese “jutaku” houses which exploit tiny urban sites to deliver some of the world’s most striking architecture. This would have the added benefit of adding new layers of interest and surprise into otherwise homogenous residential neighbourhoods.
OHouse, Kyoto, by Mitsutaka Kitamura
There are risks, of course: many planning applications are already of extremely low quality, with scant attention paid to even the most basic tenets of good design. But this, I think, is a risk worth taking. Any damage would be limited, and local.
What policy levers might be pulled to achieve it? There are several options. The first might be the use of a National Development Management Policy (NDMP). An NDMP allows the government to establish a nationwide planning policy that overrides local plans, although planning permission would need to be sought in the usual way. A second route is through a new class of permitted development within the GDPO (General Permitted Development Order). This would allow homes to be built without the need to secure planning permission, instead seeking “prior approval” to ensure that (for example) the new home considers flood risk, contamination, impact on transport and highways, and the means through which to dispose of waste and recycling. Beyond that, anything goes. The latter option would be the most credible, but the most controversial too.
The dream of designing and building one’s own home should not be out of the reach of ordinary people, and at the same time we desperately need to fill the forgotten gaps and vacant plots of our cities with as many homes as we can. Single family houses provide an opportunity for innovation and the possibility of people owning a home that is designed specifically for their needs. We should let them get on with it.
At the weekend MHCLG published a draft working paper setting out plans for a “brownfield passport”, with the intention of finding ways to make the intensification of urban areas easier.
This is long overdue. The planning system is disproportionately complex for small-scale development, and this is one of the primary reasons why the country has witnessed a collapse in the SME developer market in recent decades. In London, Barratt Homes currently builds one in ten of the city’s new homes—this is not a healthy state of affairs. I have written elsewhere about the need to provide greater certainty for small developers who are less financially resilient than their corporate counterparts.
Importantly, the document recognises the woefully low density of many of our towns and cities:
Given our relatively low densities, there is scope in many areas for increases. While such increases should take account of local character, existing character should not be used to block sensible changes which make the most of an area’s potential, and which can create sustainable, well-designed and productive places to live and work.
This is an encouraging acknowledgement, as for too long, “character” has been used as a means to refuse new homes. The draft NPPF which was published in June helpfully removes paragraph 130, which requires LPAs to refuse applications which are “wholly out of character with the existing area”. Combined with a national policy which sets out parameters for intensification, this could be powerful indeed.
Policy could, for example, say that development should be of at least four storeys fronting principal streets in settlements which have a high level of accessibility, and/or set acceptable density ranges that allow for suitable forms of intensification.
We know from previous experience that liberal design codes can be difficult for existing communities to accept. An example of this is in Croydon, where a suburban intensification policy was so hated that a new mayor was voted in just to scrap it, despite delivering nearly 2,000 new homes in a three-year period. The reason for the disgust at the Croydon policy was because it concentrated new homes in a relatively small area, and the pace of change was rapid.
How might a similarly ambitious policy, set at national rather than local level, provide certainty to small developers whilst delivering high-density development in sustainable locations? The following paragraph from the document is intriguing:
[W]e are keen to explore how this might be done – for example, whether densification in some areas should focus on corner plots and those adjoining them rather than whole streets, or linking densification opportunities to accessibility.
This makes a lot of sense. Corner developments tend to be better suited to intensification as they are less likely to overshadow or overlook adjoining gardens. They can act as wayfinding devices at key road intersections, helping bring clarity and legibility to suburban areas. And they can help provide non-residential uses such as small shops at ground floor level.
In this example a single corner dwelling is replaced with a small block of flats—four storeys in height, as it happens, as the document suggests—and provides six new homes. As Lewisham was keen not to see a net loss of family-size dwellings, this includes a pair of duplex flats with rear gardens.
Extract from the Lewisham Small Sites Supplementary Planning Document, adopted in 2021, by Ash Sakula Architects and RCKa
In outlying areas there are even more opportunities for intensification. This lovely scheme by architects Harp & Harp replaces a sprawling family home on a corner plot with no less than seven family homes. Repeating this on each of the remaining three corners of the block would result in an increase of some 24 homes; that’s almost doubling the density, with no discernible detriment to character (I’d argue a significant improvement).
Design for a new development of seven family homes in Croydon by architects Harp & Harp
Here’s another striking example by OB Architects that we included as a case study in the Lewisham SPD. It replaced a single family house on a corner plot close to South Croydon station with an attractive four-storey apartment block containing eight new homes. We should be doing this on every suburban corner.
A land-hungry detached house occupies a corner plot close to South Croydon Station.
OB Architect’s Greyfort House replaces this property with eight new homes.
So, how many of these opportunities exist? With support from MHCLG’s PropTech Round 4 funding, I’ve been developing an AI tool that can identify and characterise different types of small development plot. I’ll be writing about this more in due course, but one of the powerful features of this is that it can find combinations of different site types. For each site it assesses, the AI determines a “ranking” according to the confidence in its prediction. So, it may think that a site has a 60% chance of being an “infill” type, but also a 30% chance of being a “semi-detached” type (it could be both, of course), reducing the percentage confidence each time until it has accumulated five predictions.
Searching for sites which fit both the “corner” (ranking first or second) and “detached” categories (again, ranked first or second), for instance, reveals approximately 320 properties in Croydon which could be intensified in this way—that’s a potential net increase of around 2,000 homes. Croydon’s small sites target in the current London Plan is 6,410 homes, so this would deliver nearly a third of this total alone—as well as concentrating low-rise intensification in those areas best suited to accommodate it.
There are fewer of these sites—around 150—in Lewisham, partly because it’s a smaller borough, but also lacks the large areas of suburban development. Even so, there’s plenty of potential: take the example below, a stone’s throw from Grove Park station. My suburban intensification study suggests that this neighbourhood has a prevailing density of some 16 dwellings per hectare (dph). This is a dreadful figure for somewhere with such good access to public transport and a Public Transport Accessibility Level of 4.
This corner plot in Lewisham is ripe for intensification, with a large single-family home and deep garden, close to a suburban station, this is exactly where we should be enabling a significant uplift in density.
A development here could increase the number of homes on the site from one to fifteen or so, but as we know, local politics means that “character” inevitably takes precedence over additional homes. We cannot, therefore, rely on local policy to take the bold steps needed to intensify our suburbs: the only solution is to introduce a strategic policy that removes the potential for political interference and starts to deliver the homes we desperately need.
A national brownfield passport would be a great place to start.
“Boroughs should…recognise in their Development Plans and planning decisions that local character evolves over time and will need to change in appropriate locations to accommodate additional housing provision and increases in residential density through small housing developments.”
Draft London Plan, December 2017
I live in suburban north London, in a neighbourhood which sprang from almost nothing in the late nineteenth century with the arrival of the railway. New Barnet station is at the end of my road and my house was built on land previously bought by the railway company: we still have the original deed of transfer from 1899 which details the sale of our plot from the railway company to the developer who bought it and built the home in which I now live.
New Barnet in 1897. The railway arrived in 1850 when farmland was acquired by the Great Northern Company to enable the construction of the route, and then the land around it was sold to the British Land Company (image from National Library of Scotland).
The streets here are largely lined with Victorian terraces, with some grander villas dotted around on larger plots. Sprinkled among these are houses and flats built in the later years as a result of incremental intensification, some on the former gardens of the bigger homes, others on the site of houses destroyed by bombs in the Second World War. : There’s a handful of more recent interventions: nearby, a backland site turned into eight contemporary houses which, of course, Theresa Villiers—our local MP (for the time being)—objected to, and so on.
A typical suburban neighbourhood with deep rear gardens and lots of parking. Most of this area is less than 10 minutes’ walk from New Barnet Station (Google Maps).
Let’s Take a Ride…
Although we’re in Zone 5, trains run into town in less than half an hour; to Moorgate via Finsbury Park and Old Street, and recently our line has been connected to Thameslink, with peak-hour trains connecting commuters with the Elizabeth Line at Farringdon and on to southeast London. It’s a convenient place to live.
But, having said all of that, New Barnet—and other parts of suburban London just like it—simply aren’t that dense. Pockets of new development have been snuck into redundant land, former garages and car parks, derelict pubs and disused warehouses, and even so, the most recent Census data from 2021 tells us that the density of this part of north London is just 18 dwellings per hectare (dph). Maida Vale, as a comparison, has a density of more than five times that. And Maida Vale is hardly somewhere you could describe as an unpleasant place to live.
Whichever way you look at it, suburban London can clearly do more to meet the city’s housing needs.
A map of London showing residential densities in dwellings per hectare.
The shortage of housing in London is at crisis levels and manifests itself in many ways. Young people have been particularly badly hit, and the consequences for our economy and society are dire. In Hackney, schools are closing because young couples are unable to afford to start families. Homelessness is at record levels, with one in ten children in parts of London classed as effectively homeless. Median house prices in the capital are now 14 times average incomes while wages have stagnated. While this cannot be entirely blamed on our inability to build enough homes, it certainly plays a very large part.
Land in London is precious, yet the suburbs have a hegemony over it. Those lucky enough to own a house in the suburbs and, in particular, those living close to public transport, surely have a moral duty to allow more housing to be built around them so that others can benefit from convenient access to all of the amenities that the city has to offer.
So where might these houses go? Do we have the space? And how can we encourage intensification to happen?
Diminishing Ambitions
The current Mayor of London’s strategic plan for the city, the “London Plan”, was finally adopted in 2021 it set ambitious targets for new homes across the city, compelling each of the planning authorities to meet specific annual housing targets both, with a proportion of these to be delivered on small sites, that is any plot with an area of less than 0.25ha (about a third of a standard football pitch).
An early consultation version of the Plan was accompanied by a series of policies which provided a framework for intensification, clearly stating that boroughs needed to accept that “local character evolves over time” and that it would “need to change in appropriate locations to accommodate additional housing provision”.
I’ve written elsewhere about the push-back from many of the outer-London boroughs to this policy which resulted in the final version eviscerating the small sites targets, and Croydon’s progressive attempts to densify suburban areas that were unceremoniously chucked out by an incoming NIMBY mayor. But even in the short period of time that Croydon’s policy was in place, it resulted in a remarkable outcome, delivering around 2,000 homes within developments of fewer than 10 homes, with house prices and rents levelling off as a result.
So, what if the lessons from Croydon could be repeated across the rest of suburban London? That’s what I’ve set out to establish.
It’s about to get a bit geeky from here on in.
Cum On Feel The (Voro)nois
Using a combination of data from Ordnance Survey and Greater London Authority, I assembled a map of London and marked on it every station in the city – both Underground and mainline stations. Many stations are within 800m of each other, so I created Voronoi polygons to establish the closest station to every area in London.
A Voronoi diagram showing every station in London and the areas of the city which are closest to each.
Around each station I created an 800m diameter circle, which equates roughly to a ten-minute walking distance. By combining the two geometries I established the closest station to every area in London that’s no more than ten minutes’ walk away.
A map of London showing every area within 800m of a station.
Clearly this approach doesn’t take into account the various constraints on potential development, including lots of areas which would, of course, be impossible to build on. The Thames, for example, but also areas of protected land such as Strategic Industrial Land (or “SIL”) Locally-Significant Industrial Sites (“LSIS”), green belt and Metropolitan Open Land. There’s a discussion to be had about whether protecting any space close to stations is sensible, and whether golf courses and industrial land might be put to better use. But for the purposes of this exercise, I’ve excluded them; together with parks, gardens, sports pitches and any other type of open space. Given my focus on suburban areas, I’ve also excluded the “Central Activities Zone”, which covers central London. Further refinements exclude a buffer either side of national and regional roads, and existing railways.
The resulting map of London looks something like this:
Excluding surface water, green space, industrial land and the Central Activities Zone, this map shows all the areas in London with potential for intensification.
So now that we have a map showing all of the potential areas that might be intensified around London’s stations, we need to introduce some data which tells us more about the neighbourhoods around them.
Census Sensibility
The 2021 Census provides a huge set of data broken down into geographic zones that enables us, with a bit of mapping jiggery-pokery, to intersect them with our areas of interest.
Using Census data broken down by Medium Super Output Area (MSOA) I divided the mapping areas by the equivalent polygon areas. First, though, I ran a series of mapping exercises to establish some additional figures for each of these regions: for example, using Ordnance Survey Zoomstack data to measure the approximate coverage of buildings for each MSOA polygon. Bringing the two together enabled me to examine each of these areas in more detail. Here’s an example: MSOA ref. E02000028 which is located immediately to the west of New Barnet station.
A plan showing the boundary of MSOA E02000028, immediately to the west of New Barnet station.
Measurements taken from GIS tell us that MSOA E02000028 has a total area of 105.61 hectares, and the census data tells us that this contains 2,783 homes (45% of which are detached or semi-detached houses) – an equivalent density of about 26 dwellings per hectare. The footprint of all the buildings is about 18.7% of the MSOA, which makes sense given the large rear gardens, even though there are no large areas of open space within it. The census also tells us that, with a total population density of 62 people per hectare, the occupancy level is only 2.35 people per dwelling…which is surprising given the number of very large houses found here (the highest dwelling occupancies in London tend to be in the East End, with parts of Bethnal Green exceeding eight people per home).
You can see the hatched areas overlaid on the image above, which represent the different Voronoi polygons described early. To the bottom right of the image you’ll find Oakleigh Park station, and this MSOA is divided into three sub-areas, each part closest to a different station: in addition to New Barnet and Oakleigh Park, the north-west corner is within 800m of High Barnet Underground Station.
26 dwellings per hectare is pretty low, although not untypical of suburban London. A modest increase over this area could result in a significant number of new homes – let’s imagine for a moment that this is increased by just 25% (hardly a transformative figure). Yet, even at these modest numbers this results in 686 additional homes – an uplift in density from 26 to 32 dwellings per hectare.
Even 32 dwellings per hectare is pretty modest when compared to other parts of London. MSOA E02000589 covers the area around High Street Kensington, topping out at 137 dwellings per hectare (dph). This is probably a bit much for Zone 5, but Herne Hill (MSOA E02000642) achieves a density of 40 dph and can hardly be considered overcrowded.
With all of this in mind, I’ve established a few rules to apply to my data to try and estimate what a modest uplift in density might achieve. Arguably, nowhere in London that’s within 800m of a station should have a density of less than 40dph, so I’ve set that as a minimum. And, although some parts of the capital exceed this, I suggest that the increase in density should not push an area beyond 100dph. Within these thresholds, I’ve set a few additional rules: where detached and semi-detached houses form more than 40% of the total dwellings, I’ve set the potential density increase at 50%; where they’re less than 10% of the total housing stock, it’s 10%. For everything else I’ve assumed a 25% increase.
I’ve made a further adjustment where buildings cover less than 25% of the available land, adding a compound increase of 40% to this figure. The resultant algorithm is something like this (where “familyHouses” means a semi-detached or detached dwelling):
# First, calculate the initial uplift in density based on the proportion of "family homes"IF familyHouses > 40% THEN newDensity = existingDensity x 1.5
ELSE IF familyHouses < 10% THEN newDensity = existingDensity x 1.1
ELSE newDensity = existingDensity x 1.25
# Then add a compound density based on the total percentage coverage (footprint) of buildings over the MSOA areaIF coverage < 20% THEN newDensity = newDensity x 1.4
# Finally, if the new density exceeds 100 dph, cap the increase to this level (this means that any areas that already exceed 100dph see no increase)IF existingDensity > 100 THEN newDensity = existingDensity
ELSE IF newDensity > 100 THEN newDensity = 100
ELSE IF newDensity < 40 THEN newDensity = 40
Applied across the entire city, this results in a net increase of some 900,000 homes, with each of the boroughs seeing the following uplift:
Borough
Net New Homes
Barking & Dagenham
15,070
Barnet
54,129
Bexley
37,985
Brent
32,719
Bromley
68,426
Camden
8,625
Croydon
67,165
Ealing
34,616
Enfield
57,520
Greenwich
28,739
Hackney
10,886
Hammersmith & Fulham
9,755
Haringey
18,646
Harrow
39,122
Havering
33,385
Hillingdon
47,922
Hounslow
27,313
Islington
7,336
Kensington & Chelsea
5,537
Kingston upon Thames
27,862
Lambeth
16,601
Lewisham
31,801
Merton
23,681
Newham
26,094
Redbridge
31,856
Richmond upon Thames
31,589
Southwark
17,817
Sutton
32,490
Tower Hamlets
11,633
Waltham Forest
21,822
Wandsworth
15,593
Westminster
5,040
Total
898,776
Unsurprisingly, those boroughs with the largest area see the greatest net increase in new homes, with Bromley at the top with 68,426 new dwellings, and Croydon slightly behind with 67,165. The inner London boroughs such as Camden, Kensington & Chelsea and Westminster see the least. The City of London is at zero and doesn’t appear in this table because it’s entirely within the Central Activities Zone and excluded as a result.
It’s important to remember that the figures I’ve listed above are limited to those areas within 800m of a station. That means there’s a lot of outer London excluded from my estimates, but imagine that we increase the density here as well, perhaps by a more modest amount…there would surely be many more thousands of homes that could be built in addition to the 900,000 I’ve suggested above.
Due to limitations in the mapping data, there are some anomalies which skew the figures in a few areas. For example, the Ordnance Survey mapping data doesn’t identify football stadia within its “sites” geometry, and while I’m ambivalent about the so-called beautiful game, and would be quite happy for every football stadium in London transformed into housing, I’m not sure Arsenal fans are quite ready for the Emirates Stadium to go the same way as their former ground just yet.
Using this methodology, the Emirates Stadium is identified as a location for intensification; Arsenal’s previous ground can be seen in the top right of the image, which was converted into homes after the club moved to its new location in 2006.
There’s also no adjustment made for those areas subject to wider regeneration schemes or empty sites. The large car park to the east of Stratford Westfield, which was going to be the home of London’s version of the Madison Square Gardens’ Sphere has an area of around 2.5 hectares and could feasibly provide 200-300 homes, but my methodology only shows an uplift of eight, as the density calculation is based on the entire MSOA area rather than this small section of it.
There are some other issues which could do with refinement. The MSOA boundaries do not take into account the type of space within them so, for example, with two polygons of equal size might have varying levels of undevelopable space. The total number of existing dwellings might be the same in both cases, and therefore the overall density would be shown as equal, however in reality the same number of homes could be crammed into a smaller area. This would mean that the impact of intensification would be more profound in the latter.
In reality, though, I’m not sure these anomalies make much of a difference overall as they seem to balance out across the wider picture.
So, these oddities aside, what does suburban intensification look like when applied to largely residential neighbourhoods?
The guide provided a series of simple diagrams which mapped out the evolution of suburban blocks to show how, over an 18-year period, infilling gap sites and the replacement of some large houses with a combination of flats and houses. Let’s take a look at these to see what this means in numerical terms.
The first extract, below, shows a typical suburban block of detached houses. In the top example (2016) there are 37 detached houses. Although the plan is supposed to be a generic example, it’s almost certainly based on a real part of Croydon. There are large rear gardens and gaps of varying widths between the houses themselves.
In the “evolved” condition of 2036, several of the houses have been replaced with new buildings, and some have had new homes erected in rear gardens. From this plan it’s impossible to count the new number of dwellings that might be delivered in this way (it’s not really the point of the drawing), but the drawing does attempt to show the subdivision of the new buildings into the individual demises. Assuming nothing is taller than three storeys, I count at least 50 new homes, including a mix of houses and flats—and 29 of the original houses remain. In total, that’s a doubling of density – and it can hardly be said that the character has changed beyond all recognition: the large rear gardens largely remain and the coverage of buildings relative to undeveloped space is minimal.
This demonstrates that the kind of intensification we’re talking about is entirely achievable, and any objection on the basis of unacceptable change in character is for the birds.
Such an approach is entirely possible if we’re prepared to implement to bold policy reforms needed to enable this kind of development to come forward. In the brief period between the Croydon SPD being adopted in 2018, and it’s unceremonious scrapping in 2022, there was a remarkable uptick in small site development across the borough. The GLA’s annual Housing in London report shows that during this time Croydon delivered (delivered, not just approved) nearly 2,000 homes within developments consisting of fewer than 10 homes: more than three times the next highest, Barnet.
It’s time to adopt a London-wide policy which encourages similar levels of development across all of London’s suburbs. We know we need the homes. We now know we have the capacity. Let’s get on and do it!
You can have a play with my online map showing all areas of suburban intensification by clicking the image below.
In comparison to other similarly sized world cities, London is not very dense. With limited exceptions, such as Maida Vale, parts of Tower Hamlets and Kensington, much of the city has no more people per hectare than the satellite towns surrounding it. Arrive by train and this is only too apparent, with railways cutting through miles of two-storey Victorian terraces, only giving way to mansion blocks, high rise towers and high-density housing estates close to the heart of the city. Our housing is too thinly spread.
Map of London showing population density using data from the 2021 Census.Map of London showing dwelling density using data from the 2021 Census.
All land in London is a precious resource, and to sustain our capital’s economy and vitality we must use it more effectively—and more fairly.
Living in any major city—and benefiting from all the amenities and conveniences that it has to offer—comes with a moral responsibility to allow others to do the same. London’s suburbs could do much more to help provide the homes that the city so desperately needs—no more so than in those areas which benefit from good access to the public transport network, and where reliance on private car ownership diminishes. But in outer areas which have not been identified for large-scale regeneration, the process of intensification can be a tortuous one.
Obtaining permission to build even a small development of new homes is disproportionately complex, time-consuming and risky when compared to larger strategic developments.
Yet, even within existing planning policies, all the tools exist to establish an environment where land seemingly lost to low-density housing can be reinvigorated through a process of gradual densification.
Focusing on areas within a ten minutes’ walk of the city’s suburban train and Underground stations, there is the potential for up to a million new homes to be built, surprisingly quickly and effectively. When Mayor of London Sadiq Khan’s London Plan was adopted in 2021, it set out, for the first time, housing targets that must be achieved on small sites in each London borough.
This included the City of London Corporation and two Mayoral Development Corporations. In this case, small sites were defined as anything with an area of less than 0.25 hectares—roughly a third of a standard football pitch. Accompanying these targets was guidance and policies on how such development should be encouraged through plan-making and decisions.
Although it didn’t become formal policy until 2021, Khan’s version of the Plan had first been published in draft form at the tail end of 2017. The boroughs either embraced or resisted the Plan’s ambitions largely depending upon their political persuasion at the time. Labour-run Croydon Council, on the southern edge of the Greater London area, was one of the first out of the blocks, quickly establishing a set of planning principles to be followed by applicants wishing to bring forward small-scale development in suburban areas—generally towards the southern border with Surrey.
The award-winning Suburban Design Guide was adopted in April 2019, and provided clear parameters for the transformation of large, land-hungry houses into efficient, mid-rise developments. Essentially, if developers followed the rules established by the guidance, there would be no reason for their applications to be rejected. Some examples provided within the document demonstrated how, for example, a pair of adjoining large houses could be turned into as many as 20 to 30 new homes.
Five years on from the adoption of the guidance, which was scrapped in 2022 by the incoming Conservative mayor, there is sufficient data to demonstrate the effect.
The impact this policy had on housing delivery—and the figures are remarkable. In the four-year period between 2018 and 2021, Croydon managed to complete nearly 2,000 new homes on small sites within developments consisting of fewer than ten dwellings (noting that even this is below the London Plan’s small site threshold, which determines plot size but not the number of homes within it).
The next highest delivering borough was Barnet, which in the same period delivered around a quarter of this figure.
Extract from Croydon’s Suburban Design Guide Supplementary Planning Document.
The Suburban Design Guide neatly illustrated how larger areas of suburban housing could be intensified incrementally, resulting in a broader mix of smaller flats, townhouses, and large family homes. This is exemplified above showing how two large homes could be replaced with a block of flats and eight townhouses. This approach is borne out by the number of homes delivered in Croydon during a relatively short period of time: around 500 per year. There are 20 outer-London boroughs including Croydon.
If the remaining 19 had managed to deliver housing on small sites at the same rate, we could have had another 25,000 homes built by now.
Extract from 2023 Housing in London report by the GLA showing the number of homes delivered on small sites, and with fewer than ten homes.
Suburban intensification is tricky, and alone will never be able to deliver all the homes that London needs. But experience from Croydon has demonstrated that when the right conditions are in place, it can be implemented quickly, and at scale. As the country recovers from a long period of stagnation, this is one way that we can not only build the homes we need—quickly, where they’re most needed—but also promote economic growth.
This article was originally published in the Fabian Society pamphlet “Homes for London” in April 2024
A map of Lewisham showing the distribution of potential small sites as found by AI
When the latest iteration of the London Plan was adopted in 2021, for the first time in its 20-year history the policy demanded that the capital’s 35 planning authorities deliver a proportion of their overall housing targets on small sites – that is, with an area of no more than 0.25ha. The figures varied across the city, but the total number of homes to be found on these pockets of land stood at 120,000 – just under a quarter of the overall housing target for the whole of London.
This number was way below that originally proposed by the London mayor in 2018. Alongside a ‘presumption in favour’ of development on small sites close to public transport, the earlier version of his plan compelled planning authorities to find space on small sites for a quarter of a million homes, with the outer boroughs expected to deliver the lion’s share.
The pushback was inevitable, with London Assembly member Andrew Boff claiming, hyperbolically, that this amounted to a ‘war on the suburbs’. With the GLA lacking convincing data to demonstrate the figures were achievable, the targets were slashed before adoption.
But quiet, in the background, progressive boroughs knuckled down and got on with putting plans in place to promote intensification. In 2020 – nearly a year before the final version of the London Plan was adopted – Lewisham Council appointed RCKa and Ash Sakula to prepare dedicated guidance for new homes on its small sites. Just six months after the London Plan became official policy, Lewisham’s Small Sites SPD was formally adopted.
Two years on, as Sadiq Khan looks towards what’s increasingly likely to be a third and final term, he will be considering updates to the London Plan to cement his legacy as the mayor who did the most to tackle the city’s profound housing crisis. Small sites are likely to be a key focus of this work, and it would be a shrewd move to ramp up the small sites targets accordingly. But the question remains over whether there is sufficient data to justify this increase. To counter resistance to suburban intensification (as happened in Croydon) the new plan will need to be backed with robust evidence of the quantity and distribution of these sites.
So where are they? And how many? We tried to find out.
Land Registry data tells us that there are some 66,000 freeholds in Lewisham, and about 85 per cent of these meet the small-site criteria. Armed with our intimate knowledge of the Lewisham SPD and the site “types” it identifies, we set about mapping every one of them. Having built up a vast library of sites, based on the SPD, we trained an AI to categorise a bunch: backland, infill, amenity space and so on. Then, setting our learning model on the remainder of the borough, we created a complete map of Lewisham, including the location, size – and a rough idea of capacity – of every development opportunity from Deptford to Beckenham.
What we found was striking. While Lewisham’s London Plan 10-year small sites target is currently 3,790, based on early outputs from our data we think there might be capacity for two to three times this number. In fact, our AI model shows that there are enough sites to deliver Lewisham’s target on just two types alone. And as we trawl through the data, the AI improves. Ultimately, our plan is to apply the learning model to capture the whole of London.
Now, just because a site is developable it doesn’t mean it will come forward. The AI makes no distinction between public and private ownership, and many of the sites it has picked out will not provide new homes: some are private gardens, others active builder’s yards and occupied garages. But by establishing a policy landscape that makes planning less risky – as Lewisham has done – boroughs can go a long way to meeting these targets.
Extrapolating these figures across the rest of London, we think there’s sufficient capacity for at least 350,000 homes. Backed by our AI, there can be no more arguing over targets when we know not just how many sites there are. We can even point to them on a map. This is a huge opportunity, and those boroughs still lacking a dedicated small-sites policy should be compelled to implement it as soon as they can. It’s time to take small sites seriously.
Announced with considerable fanfare in 2018, and becoming formal planning policy the following year, Croydon Council’s Suburban Design Guide supplementary planning document (SPD) was London’s first – and, even now, most ambitious – attempt at encouraging its woefully sparse outer areas to do more to meet the city’s housing needs.
The publication made no bones about its intentions. “The evolution of the suburbs to provide homes that will meet the needs of a growing population,” its introduction stated. It went on: “It must however be recognised that delivering approximately 10,000 homes in the suburban places of Croydon will result in an evolution of the existing character of suburban streets, and that the increased density of homes can impact on the amenity of existing residents if not properly managed.”
The guide was rightly heralded as a progressive and practical attempt to deliver new homes in those places best able to accommodate them, and it was quickly celebrated as an exemplar for how to sustainably densify the city’s fringes. Croydon’s in-house spatial planning team took home a planning award in 2019 and the guide was highly commended at the New London Awards the same year. From a personal point of view, it was an important reference for my architectural practice’s own small sites SPD in Lewisham, which was adopted by the council a year ago this month.
However, just three years on, Croydon’s Suburban Design Guide is no more. In May, the borough’s voters elected Conservative Jason Perry as their first Mayor. He had promised that one of his first acts if he won would be to revoke the “dreaded” SPD, which he claimed has “destroyed” Croydon’s character and led to the “destruction” of homes – a peculiar claim given the huge number of dwellings it had in fact enabled in a relatively short time.
The SPD had been produced in response to Sadiq Khan’s London Plan, which was first published in draft in 2017 but not formally adopted until March 2021. The Plan enshrined the need for the boroughs to consider the importance of small sites in meeting London’s housing needs. For the first time, every London planning authority was tasked with finding ways to encourage development on sites with a total area of less than a quarter of a hectare (roughly one third of a standard football pitch), with a ten-year small-site housing target set out in unequivocal terms.
Not only was this to be a way of delivering much-needed homes, the Plan also acknowledged the importance of nudging small-scale developers back to a market that had become dominated by a handful of volume housebuilders since the 2008 financial crash.
Inevitably, the draft Plan’s publication was met with hyperbolic outcry: a “war on the suburbs” is how Conservative London Assembly member Andrew Boff described the proposals, oddly failing to recognise that small-scale infill development tends to deliver a higher proportion of family homes than small flats; another bête noire of his.
After a robust challenge from several outer London boroughs, Khan was forced to dramatically reduce the small sites housing targets and blunt the “presumption in favour” the Plan had demanded. Having been required to deliver the highest absolute number of homes on small sites of any of the London planning authorities, Croydon Council received the greatest net reduction, with its ten-year target reducing from 15,110 to 6,410 – a drop of nearly 60%.
Croydon is one of London’s least dense boroughs, even when its 2,300 hectares of Green Belt and Metropolitan Open Land are excluded from the calculation. At 65 people per hectare, it has around a third the population density of Islington. Its number of homes per hectare is broadly the same as other similarly sized outer boroughs, such as Barnet and Kingston. And, like those boroughs, it clearly can accommodate many more.
In its defence, Croydon has delivered a lot of new homes in the last decade and a half—more than any other borough—so it’s perhaps fair to argue that the council had indeed “played its part” in meeting the city’s housing need. Yet the figures are misleading. Much of Croydon’s new development is concentrated in the urban centre, where clusters of tall residential towers have sprung up around East Croydon station within easy reach of central London.
This is good. Less good, however, is the quality of much of this new housing. Until halted by the implementation of an Article 4 Direction, more new dwellings were created under dubious permitted development rights, which allow commercial buildings to be cheaply converted to residential outside conventional planning permission, in Croydon than in any other borough. It’s not a statistic to be proud of given the sub-standard quality and small size of many of them. Until the introduction of the Suburban Design Guide, the leafier southern wards had got away without making much of a contribution.
Aware of the inherently risky nature of small sites, and that developers interested in taking them on are less able to absorb the cost of delayed or unpredictable planning decisions, the guide presented a series of suburban intensification methods which, if employed, were highly likely to be nodded through.
The acquisition of a pair of suburban semis – of which Croydon has many thousands – could easily lead to their replacement with a small block of flats at the front of the plot and mews houses in the rear garden. In this scenario, there could be a net gain of up to ten homes with no loss of family housing. The guide demanded that new development be no lower than three storeys – a not unreasonable request if we are to have any hope of densifying London’s laughably sparse peripheral areas.
Of course, this inevitably meant that some areas of the borough would experience some change, but that is a small price to pay for living in this great city. There would be benefits too. As the guide’s introduction made clear, higher housing density inevitably attracts local amenities and better social infrastructure – shops, restaurants, schools, healthcare and community facilities – that might actually mean suburbanites wouldn’t need to hop into their giant SUVs quite so often.
It’s no surprise that those areas most resistant to the principle of intensification tend to lie on the city’s fringes, and often consider themselves to be residents of the Home Counties rather than London. The Green Belt itself is often declared as an unnecessary and anachronistic constraint on the capital’s growth. There is some truth in this, but we should start by turning our attention inwards a little: it is the sparsely populated “greyfields” of outer London we need to tackle first.
The citizens of the suburbs must accept that the evolution of local character is a small price to pay for easy access to everything this wonderful city has to offer – and that it is also their duty to enable others to do the same. Croydon’s Suburban Design Guide was a valiant and progressive attempt to achieve this. We should mourn its passing.
This article was originally published by OnLondon.
Take a stroll around any London suburb and before long you’ll come across a pocket of land – a row of garages too small for modern cars, an overgrown gap of uncertain ownership nestled between houses, a sliver of broken concrete beside a railway line – which, with a little tenacity and creativity, could provide space for a new home or two. These sites exist in their thousands across London and are particularly abundant in the outer fringes of the city.
London itself is not very dense. Islington, with around 160 people per hectare, is the borough with the greatest number of people relative to its size. Bromley, with the smallest, has 22 people living in the same area. Compared to Paris and Madrid (neither of which could reasonably be described as unpleasant places to live), with figures of 213 and 286 per hectare respectively for the cities as a whole, it’s clear that London should be able to accommodate far more people than it already does.
In his version of the London Plan (the blueprint for London’s growth over the next ten years) Sadiq Khan set out ambitious targets for the delivery of new housing across the capital. Where the previous mayor, Boris Johnson, adopted a “blue doughnut” approach to planning, which capitulated to the Outer London, largely Conservative-voting, boroughs’ demands for more autonomy over planning decisions, Khan initially required those very councils on the edges of the city to do more to help deliver new homes. As an example of this new approach, Merton’s housing targets rocketed from just over 4,000 in the Johnson’s version of the London Plan to more than 13,000 in Khan’s – an increase of nearly 225 per cent.
For the first time, a key strategy of the Plan was the exploitation of small sites to help achieve overall housing targets. (Small sites, in this context, are defined as those providing up to 25 homes). Previous Plans had ignored the potential of such sites to make a significant dent in housing targets, largely because their capacity was so hard to quantify. Yet under the current Mayor this was to become an important component of the new housing strategy. In total, it required no less than 245,730 homes to be delivered on small sites over ten years—more than a third of the total housing target for London over that period.
To compel insubordinate councils to comply, the Plan included a controversial clause requiring them to adopt a “presumption in favour” of approval for small developments on sites close to stations or high streets, at the same time acknowledging that the character of some areas would need to evolve to accommodate London’s anticipated population growth.
Predictably, this was met with a hyperbolic response from Conservative politicians, with Andrew Boff, leader of the Tory group on the London Assembly, claiming that the policy amounted to “war on the suburbs”. Yet a less partisan analysis clearly shows that the Outer London boroughs are not doing nearly enough to combat the housing crisis. Even the government’s own, less ambitious, targets demonstrated that several of the suburban boroughs are falling short, with Havering achieving only a third of its target.
Prior to becoming official policy, any new London Plan has to go through a process of public consultation and interrogation by an independent planning inspector. With Mayor Khan’s draft new Plan, this took place in spring of 2019, with a queue of homeowning suburbanites duly trotting up to City Hall to lambast the Mayor’s proposals. Complaints were raised about the complex statistical methods for calculating the capacity of Outer London to deliver new homes and familiar, tired accusations that a wave of “garden grabbing” would be unleashed were made. Inevitably it was the least dense boroughs – and therefore the ones with the greatest capacity for growth – which pushed back hardest against the Mayor’s proposals.
The outcome of the examination was a resounding rejection of the small sites policy by the inspector, who called for its wholesale removal. A recently as November the Mayor rejected this call, claiming that London could indeed “deliver those homes within London’s boundaries with no development on the Green Belt” (the latter stance, by the way, was something else the inspector had recommended the Mayor reconsider). However, when the Mayor’s final version of the Plan appeared in December, the small sites policy was almost entirely gone – and with it the associated housing targets. In some cases the numbers had been slashed by half. Across London, this resulted in a total reduction of 125,000 potential homes.
What was the reason for this extraordinary change of heart? With an election looming, perhaps the Mayor was hopeful of making a political play for support in those boroughs currently holding fast against the red tide? After all, eight of the ten biggest reductions for small sites targets were in non-Labour voting boroughs, the same number that voted Conservative in the 2016 mayoral election. Perhaps it was felt that this policy risked holding up adoption of the Plan? That seems possible, though recent criticism by secretary of state for housing Robert Jenrick suggests that the government considers the Plan not to be ambitious enough. In his letter to the Mayor, Jenrick also objected to the Plan’s emphasis on building flats rather than family houses – something that small sites tend to deliver.
The idea that the suburbs continue to represent a bucolic escape from the grime and overcrowding of Inner London has long been anachronistic. With home ownership in the central boroughs now out of reach for most, Outer London is increasingly proving an acceptable compromise between commuting and housing costs. Change in the character of Outer London is inevitable as the city adapts to growth, yet in reality even the more ambitious small sites targets of the Plan would hardly have resulted in noticeable change in the character of suburban neighbourhoods. Dividing large houses into flats, small-scale development on infill sites, utilising scraps of redundant land and above shops: all of these count against the figures, and when spread across a wide area would barely be noticeable, even with the higher targets.
The claim that suburban boroughs are unable to deliver their fair share of the homes is preposterous: under the latest, less ambitious, version of the London Plan, Hackney – with a total area of 1,900 hectares – is, over the next decade, expected to deliver 6,580 homes on small sites compared to 2,950 in Hillingdon, despite the latter having an area six times larger. Inevitably some standards must change: policies that require a minimum distance between windows of no less than 20 metres, as is the case with many suburban boroughs, are no longer fit for purpose in a rapidly densifying city. As has consistently been pointed out by campaign group Create Streets, many of the older homes considered desirable today would not comply with contemporary planning policies.
The removal of the small sites policy from the London Plan represents a betrayal, not only for those citizens of London desperate to get a foot on the housing ladder but also for all of those small businesses so vital to the city’s construction economy: builders, developers and design professionals, for whom the risks inherent in the planning and delivery of small-scale developments are often too great to justify. With the last-minute extension to the Mayor’s term due to the coronavirus we can only hope for the reintroduction of the small sites policy so that we can get on with delivering the homes London needs.
This article was originally published by OnLondon.
