Housing development in London has a new weapon: AI

Data from an AI learning model that mapped the London Borough of Lewisham suggests the capital’s targets for ‘small site’ development could be radically increased, says Russell Curtis

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.

This article was originally published in the Architects’ Journal.


Procurement Using 50% Scoring Ratio

This describes a typical limited tender process using standard methods of price / quality measurement, with a pricing ratio set at 50%. It demonstrates that this scoring ratio will almost certainly result in the cheapest price winning the project, even with a very low quality score.

The sample scores used to test this model is as follows:

Bidder NameFee (£)Quality Score (Out of 100%)
Practice A 102,45082
Practice B78,00075
Practice C125,15085
Practice D98,50068
Practice E25,00025
Practice F107,00076

Note that the scoring for Practice E has deliberately been set very low, scoring just 25% for quality but also coming in at less than a third of the next cheapest bid. Unfortunately, such wild variations in price scoring are not unusual when bidding for public sector work. There are few other sectors where any sensible person would accept a tender which was so much lower than the broad average of others; yet, for architectural services, such low-ball bidding is common—and rarely rejected, despite the Public Contract Regulations allowing commissioning bodies to reject “abnormally low” bids. Given that architectural salaries are broadly similar, the only explanation for low fees is that the bidding practice is anticipating spending far less time working on the project than others. There are no innovations in the market which enable practices to significantly reduce the cost of delivering their services without reducing amount of time spent performing it, and therefore the quality of the design which derives from these efforts.

For the purpose of this exercise, the most expensive practice has also scored the highest for quality. This is useful to demonstrate how different scoring methods can achieve a reasonable balance between quality and price, delivering best value for the client.

The following sections explore different methods of scoring and, using the figures above, illustrates how different ratios and scoring methods result in very different outcomes.

Relative to Cheapest Method of Scoring

In our example, the lowest financial bid was £25,000, and the highest £125,150. Scoring was based on a quality / cost ratio of 50:50.

The highest quality score was 85% which, when adjusted to the quality ratio of 50%, results in a quality component of 42.5%.

Using this method of scoring, Practice E (the cheapest) is the winning bidder. Clearly, any practice securing work with a fee of less than a third of the nearest bidder is either going to be unable to service the project properly or will be making a significant loss. Nobody in their right mind would accept such a low tender from, say, a builder, as clearly the quality of the work would be commensurately poor. Yet this happens all the time when it comes to commissioning architectural services.

RankingBidder NameFee (£)Price Score (%)
(max. 50.00)
Quality Score (%)
(max. 50.00)
Total Score (%)
1Practice E (WINNER)25,00050.0012.5062.50
2Practice B78,00016.0337.5053.53
3Practice A102,45012.2041.0053.20
4Practice C125,1509.9942.5052.49
5Practice F107,00011.6838.0049.68
6Practice D98,50012.6934.0046.69

Out of interest, let’s test the same figures using an alternative ratio: 70% quality and 30% price. This gives us the following results:

RankingBidder NameFee (£)Price Score (%)
(max. 30.00)
Quality Score (%)
(max. 70.00)
Total Score (%)
1Practice C (WINNER)125,1505.9959.5065.49
2Practice A102,4507.3257.4064.72
3Practice B78,0009.6252.5062.12
4Practice F107,0007.0153.2060.21
5Practice D98,5007.6147.6055.21
6Practice E25,00030.0017.5047.50

This result isn’t ideal either, as now the most expensive bidder has won the day, with a quality score that’s only marginally higher than the nearest competitor, but a pricing score which is a fifth higher.

Perhaps this suggests that the relative to cheapest method of scoring is never the best one to use?

Relative to Best Method of Scoring

An alternative way of assessing quality is to award all of the available quality points to the best submission. Having established a shortlist of what are, presumably, the most capable qualifying competitors on the market, it is nonsensical that the cheapest price tender receives the full 50% of the price score, but the best submission does not receive the full 50% of the available points for quality.

It may be that assessors have already given the best submission the full available score for quality, but if not, this method assesses all quality scores relative to the maximum percentage available, as well as giving the maximum marks for price to the cheapest bid. In other words, the best quality submission receives the whole 50% available, with all the remaining scores calculated proportionately to this.

It goes some way to preventing the cheapest bid “buying” a project with an inferior submission accompanied by an abnormally low financial submission—but does it ensure that the client is receiving the best value for money?

In this example, and using the same 50:50 ratio, Practice E still wins, having scored 50.00% for price and 14.71% for quality. So, pursuing this method doesn’t seem to make much difference.

RankingBidder NameFee (£)Price Score (%)
(max. 50.00)
Quality Score (%)
(max. 50.00)
Total Score (%)
1Practice E (WINNER)25,00050.0014.7164.71
2Practice A102,45012.2048.2460.44
3Practice B78,00016.0344.1260.14
4Practice C125,1509.9950.0059.99
5Practice F107,00011.6844.7156.39
6Practice D98,50012.6940.0052.69

Mean Narrow Average Method of Scoring

The mean narrow average (MNA) method of scoring discounts the highest and lowest tenders, establishing the mean value of those that remain, and scores all tender prices against the closest to that mean value. Fee bids which are less than half, or more than double, the mean value receive a price score of zero.

With Mean Narrow Average scoring, bidders are compelled to identify the appropriate fee required to service the project rather than cutting prices to buy the job, which could lead to underperformance or claims for additional fees later in the programme. Excessively low—or high—fees are penalised.

For these pricing figures, the mean (average) bid, including the lowest and highest fee submission, was £89,350, and the median was £100,475.

The highest and lowest fee bids have been excluded when calculating the mean average.

Using Mean Narrow Average with a price ratio of 50% results in Practice A being the winning bidder. Intuitively, that seems like a reasonable result: Practice A scored very close the median score (there were two more expensive bids, and three cheaper ones), and scored second highest in terms of quality. The full rankings are as follows:

RankingBidder NameFee (£)Price Score (%)
(max. 50.00)
Quality Score (%)
(max. 50.00)
Total Score (%)
1Practice A (WINNER)102,450.0046.9141.0087.91
2Practice D98,500.0048.9634.0082.96
3Practice F107,000.0044.5538.0082.55
4Practice B78,000.0040.4237.5077.92
5Practice C125,150.0035.1542.5077.65
6Practice E25,000.000.0012.5012.50

Alternative Ratios

To test a few alterative scenarios, I’ve run the same figures as above, but using different price/quality ratios. In most cases, the outcome is the same: Practice A wins, right up to the point where price comprises just 10%. Then, the highest scoring quality submission—and the most expensive bid—is the one that’s successful.

This means that the use of Mean Narrow Average is probably best deployed with a quality/cost ratio of around 60% – 70%.

Quality: 60%, Price: 40%

RankingBidder NameFee (£)Price Score (%)
(max. 40.00)
Quality Score (%)
(max. 60.00)
Total Score (%)
1Practice A (WINNER)102,450.0037.5349.2086.73
2Practice F107,000.0035.6445.6081.24
3Practice D98,500.0039.1740.8079.97
4Practice C125,150.0028.1251.0079.12
5Practice B78,000.0032.3445.0077.34
6Practice E25,000.000.0015.0015.00

Quality: 70%, Price: 30%

RankingBidder NameFee (£)Price Score (%)
(max. 30.00)
Quality Score (%)
(max. 70.00)
Total Score (%)
1Practice A (WINNER)102,450.0028.1557.4085.55
2Practice C125,150.0021.0959.5080.59
3Practice F107,000.0026.7353.2079.93
4Practice D98,500.0029.3747.6076.97
5Practice B78,000.0024.2552.5076.75
6Practice E25,000.000.0017.5017.50

Quality: 80%, Price: 20%

RankingBidder NameFee (£)Price Score (%)
(max. 20.00)
Quality Score (%)
(max. 80.00)
Total Score (%)
1Practice A (WINNER)102,450.0018.7665.6084.36
2Practice C125,150.0014.0668.0082.06
3Practice F107,000.0017.8260.8078.62
4Practice B78,000.0016.1760.0076.17
5Practice D98,500.0019.5854.4073.98
6Practice E25,000.000.0020.0020.00

Quality: 90%, Price: 10%

RankingBidder NameFee (£)Price Score (%)
(max. 10.00)
Quality Score (%)
(max. 90.00)
Total Score (%)
1Practice C (WINNER)125,150.007.0376.5083.53
2Practice A102,450.009.3873.8083.18
3Practice F107,000.008.9168.4077.31
4Practice B78,000.008.0867.5075.58
5Practice D98,500.009.7961.2070.99
6Practice E25,000.000.0022.5022.50

Out of interest, what happens is we reverse the ratio to prioritise cost over quality, using the Mean Narrow Average scoring method? Well, here we go:

Quality: 20%, Price: 80%

RankingBidder NameFee (£)Price Score (%)
(max. 80.00)
Quality Score (%)
(max. 20.00)
Total Score (%)
1Practice D (WINNER)98,500.0078.3313.6091.93
2Practice A102,450.0075.0616.4091.46
3Practice F107,000.0071.2815.2086.48
4Practice B78,000.0064.6715.0079.67
5Practice C125,150.0056.2417.0073.24
6Practice E25,

Surprisingly (at least to me), Practice A still scores very highly, coming second to Practice D which had a similar, but slightly lower price, but the second-to-bottom quality score. Nobody in their right mind would advocate for the commissioning of architectural services based on such a skewed ratio, but this serves to demonstrate that our earlier conclusion that a quality ratio of between 60% and 70% is likely to yield the best outcome for everyone.

A combination of Mean Narrow Average (MNA) and Relative to Best scoring methods could also be used, i.e. where the price score is calculated as the MNA result with the highest quality score receiving all of the points available, but given the success of the simple MNA method, it’s probably unnecessary.

All of these figures have been generated using a live model which you can test with different figures of your choice, here. And if you’re a procurement officer or public client, try putting so real-life tender figures you’ve received into this too, and see whether the outcome would have been any different.


After posting this article on LinkedIn, I’ve been directed to a comprehensive analysis of the various pricing models available to the public sector, written by Rebecca Rees of Trowers & Hamlins, which sets these out far more comprehensively than I could ever hope to do.

You can download the document using the button below.


Britain’s Green Belt is Choking the Economy

My research into rural train stations’ potential to deliver millions of homes is mentioned in this article in the Economist.


Sadiq Khan should be bold. He should rethink the green belt

No aspect of planning policy is quite as divisive, or as misunderstood, as the green belt. Covering some 16,000km2, England’s 14 green belts occupy one-eighth of England’s total area (equivalent to three-quarters of the area of Wales, if that’s your preferred unit of measurement).

London’s metropolitan green belt alone stretches from Haslemere in Hampshire to the North Sea—a distance of some 100 miles—and with an area of over half a million hectares is over three times larger than the city itself.

Although its origins precede the Second World War, the green belt was formally established by the Town and Country Planning Act of 1947, which allowed planning authorities to protect open space with this designation. And while the policy has been extremely successful in achieving its original objective of constraining urban expansion, three-quarters of a century on, it’s surely time to reform this anachronistic policy and ensure it meets the needs of the modern world.

Among the marshes of estuary Essex and the undulating hills of Hampshire, there are motorways, waste transfer depots, landfill sites, distribution centres, poultry farms, golf courses and car parks that are all protected from development by the simple virtue of their presence within the green belt. Many areas of otherwise undeveloped space are of limited quality too.

One of the most prominent obstacles to a sensible discussion is the fact that the arguments for and against the green belt have become so utterly polarised. Listening to both sides of the debate, you’d be forgiven for thinking that we face a simple binary choice between the preservation of dwindling landscapes and concreting over every last inch of them. And yet, the green belt has actually grown in recent years. It’s preposterous to claim that it’s under threat.

While we can’t lay the blame for our pitiful national productivity solely at the feet of green-belt policy, it’s clear that our inability to build – whether it’s homes, railways or solar farms – in the places we need, is partly a product of misplaced constraints on development.

Lobby groups like the Campaign for the Protection of Rural England (CPRE) insist that any rethink of the green belt isn’t necessary, but these claims simply don’t stand up to scrutiny. Its latest State of Brownfield report confidently concluded that 1.2 million homes could be built on brownfield land alone, but this is only a quarter of the current shortfall, and certainly insufficient to meet future demands. Furthermore, many of the areas it proposed for new housing aren’t even in the places where need is most acute. I’m not aware of many CPRE members upping sticks from leafy Surrey to the post-industrial wastelands of northern Britain.

There’s a common misconception about the purpose of the green belt in the public sphere, with many mistakenly believing that its purpose is to protect precious rural landscapes. Close to where I live, campaigners against the Cockfosters car park development argued that planning permission should be refused because it would be visible from the green belt, as if the prospect of catching a glimpse of it whilst hurtling along the M25 was a prospect so horrific it didn’t bear thinking about.

In a poorly researched article in the Guardian, Simon Jenkins recently pondered why there wasn’t the same level of protection for the country’s rural parts in the same way that our cities are preserved by Conservation Areas. Any architect or planner could have pointed him towards a whole bunch of protections: AGLV, AONB, Ancient Woodland, SSSI, Ramsar and National Parks, to name a few. Rural areas in fact benefit from far more protections than our towns and cities do, but this is indicative of a wider misunderstanding of planning policy, where green belt is wrongly conflated with other designations that actually do pertain to landscape quality and biodiversity.

It is true that too many open spaces have been relinquished to low-quality, car-dependent sprawl, and nobody – other than the volume housebuilders – wants to see more of that. But, despite what the CPRE claims, we cannot build the homes our country needs on brownfield alone, so some release of open space is inevitable and probably desirable.

There’s a compelling argument that green-belt policy is actually damaging the valuable open spaces that the CPRE is keen to protect. Because building homes is so difficult in places with large areas of green belt, developers target sites beyond it, creating their unsustainable car-dependent sprawl on the outskirts of settlements instead.

Likewise, building new homes on brownfield land far from public transport makes little sense when we could instead cluster them around stations in rural areas, and as an added bonus, give millions of families convenient access to the countryside – something the CPRE claims to support. Not that this should be a free-for-all. Any release of green-belt land for development must be accompanied by robust masterplanning and design codes to ensure that when land is set aside, it is done in a way that is sustainable, accessible, and responsive to local character.

The amount of green belt that would need to be lost to provide a million new homes is so small that it’s little more than a rounding error. Even with modest densities, we’d lose just 1 per cent of the green belt to deliver a million homes. That’s a price worth paying.

Labour’s recent pronouncements in this respect are welcome – if vague . But there are encouraging signs from planning authorities, such as Enfield, that are prepared to tackle this challenge head-on. And emboldened by a lacklustre field of opposition candidates, the mayor of London might revisit his blanket opposition to green-belt release in the next iteration of his city-wide spatial plan. We can but hope.

It’s surely time to set ideology aside and face the fact that an evidence-based review of green-belt policy is long overdue. If we’re to have any chance of facing the challenges of the coming decades, we need to roll up our sleeves and, maybe, loosen our belts.

This article originally appeared in the Architects’ Journal.


Rural stations are the key to building 1.2m homes in the right places

Perhaps we’ve been desensitised to the stark realities of the housing crisis, with the ‘keep calm and carry on’ attitude of the baby boomer generation (which, we need to remember, lived through very little genuine hardship in the post-war years) prevailing. But in other any functional democracy where 3.6 million young adults remained at home due to generational housing inequality, this would be a national scandal. According to some estimates, we are millions of homes short of where a country with our population should be.

The fact that none of the mainstream parties have yet to articulate a plan to address this crisis is a damning indictment of current political discourse. Not only is this a social failure, it’s an economic one too. Productivity in the UK is woefully low, with young people unable to relocate to where jobs are, or otherwise struggling with extended commutes. Worse still, a generation is delaying starting families as housing costs, employment precarity and overcrowding threaten to detonate a demographic time-bomb which nobody seems willing to defuse.

I live on the northern fringes of London, the final stop before the railway plunges into the capital’s green belt. In less than 30 minutes I can be in central London, on one of six or more trains that run every hour. There are many similar lines that extend out of London, providing convenient access both to the city and countryside for those who live close to them. It’s difficult to think of more appropriate locations for new homes.

Resistance to urban expansion is often (rightly) based on a fear of perpetuating low-density, car-dependent sprawl on the outskirts of our rural towns and villages. So it follows that, in order to create new homes less dependent on private vehicle ownership, we should instead look to optimise development around existing public transport networks. But how many homes might we build? And where?

Using various publicly-accessible data sources, I mapped every train station in England and examined the constraints on development around each. Anywhere at risk of flooding was excluded, as was land within national parks, existing urban areas, or those sites protected by landscape designations because of their quality or scientific interest. Green belt, though, I considered fair game: regardless of what the CPRE claims, it’s increasingly clear that we cannot deliver the homes we need on brownfield alone, and a pragmatic review of green belt policy is long overdue. Drawing an 800m radius around each station (equivalent to a 10 minute walk) and extracting constraints, I arrived at a pleasing 777 stations with development potential.

Not every one is close to a population centre, and some are used by only a handful of passengers each year. As there’s no easy method of measuring current or potential frequency of service, I pegged target densities to passenger annual numbers. Those stations closest to major cities were assigned 75 homes per hectare, those in remote areas much less. But even at modest densities this reveals a huge potential for delivering the new homes we need.

A case in point: Ashwell & Morden sits mid-way between London and Cambridge, with frequent services to both. Yet look at it on Google Maps and you’ll see the station is surrounded by little more than open fields. It’s not even in the green belt of either city. Even at modest densities, this site could accommodate 7,000 homes for some 30,000 people. Development of this scale, supported by a decent masterplan and robust design coding, could provide social infrastructure and sustainable travel for residents. And rolling out a similar approach to the rest of the country could be transformational in providing high-quality homes in sustainable locations such as this.

The familiar complaint from those in comfortable circumstances that we risk ‘concreting over the countryside’ doesn’t stand up to scrutiny when – even with these additional numbers – we’d lose less than 0.4 per cent of England’s rural space in the process (Britain’s roads take up around three times this area).

The coming general election could be a turning point in whether we take genuine steps to address generational inequality, particularly in respect of housing delivery. Building homes around rural stations won’t go the whole way to achieving this but, combined with other bold ideas, it could play a part.

This article was originally published in the Architects’ Journal.


Croydon’s Conservative Mayor has put suburban resistance before home building

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.


Supporting Planning Applications for New Homes

Together with campaign group PricedOut, I’ve written a brief guide on how to support planning applications for new homes.

The planning system is too often skewed in favour of those who object to new housing in their area, so this guide sets out how those with little knowledge of how planning works can register their support for much-needed new housing.


The removal of the small sites policy from Sadiq Khan’s London Plan is a betrayal

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.


Heart of the matter: Why architects need a key role in the construction process

To find an architect lamenting the erosion of the profession’s role within the construction process may elicit from many little more than crocodile tears or, to others, smack of a futile act of self-preservation when faced with challenging financial targets, shrinking capital budgets and the avoidance of risk. But while architects’ railing at the demotion of quality in favour of ‘certainty’ is hardly new, events of the last year have suddenly thrust our concerns into the spotlight.

It is still far too early to apportion culpability for the horrific fire at Grenfell Tower in June, but it is possible that this may emerge as the latest, and most tragic, manifestation of decreasing oversight that architects have been warning about for so long. At the very least, there is clear evidence that a lack of professional, independent scrutiny has resulted directly in catastrophic failures elsewhere that could – had circumstances been only very slightly different – have resulted in tragedies of their own.

One example is the Edinburgh Schools fiasco, where Professor John Cole’s extensive inquiry into the collapse of a masonry wall at Oxgangs School in Edinburgh identified clear areas where a lack of oversight during the construction process phase had allowed poor workmanship to creep, unchecked, into the works.

Crucially, it became apparent that this was not an isolated incident, but one which was found to be endemic in the wider schools delivery programme, with a further four collapses directly attributed to workmanship not in accordance with the consultant’s designs. Professor Cole determined that independent scrutiny would likely have prevented such incidents occurring.

As well as the obvious risk to life, such events have had a dramatic financial and personal impact, with hugely expensive rectification work and extensive disruption to the education of students the new buildings were supposed to enhance.

There are innumerable, less spectacular, examples to be found throughout the country, many resulting in minor irritations but others which dramatically affect the enjoyment of buildings by those who inhabit them; in some cases, such as the Orchard Estate in east London, the result of a poor quality construction process and a lack of oversight has had a detrimental effect on residents’ quality of life.

It is a criticism often levelled at architects (and one not entirely without merit) that we have allowed ourselves to be pushed to the margins of the construction process, becoming adept at piloting complex schemes through an increasingly tortuous planning process, but superfluous when it comes to putting the thing together on site. One consequence of a decade of austerity is the presence of many young architects rising through the ranks of the profession for whom an understanding of construction techniques remains an abstract concept; lines on a drawing that have no analogue on a muddy building site.

While there’s some truth in this, in reality our marginalisation extends back far further than the recent financial crisis, with our traditional role at the heart of the construction process having diminished gradually as contractors, and other professionals, stepped into a void that we only had a small part in creating.

A shift away from what came to be known as ‘traditional’ contracting and the adoption of so-called ‘collaborative’ forms of contract, exemplified by design and build, were conceived as a way of reducing the adversarial nature of construction in the hope that by working together the entire team could focus on delivering projects to programme and budget.

It was expected that D&B would magically reconcile the elusive triumvirate of cost, quality and time. What really happened was a transfer of risk, with the balance of power shifting from the contract administrator (a role most often fulfilled by the architect) to the builder.

With the architect no longer acting on behalf of the client, and often taking their place as just another subbie within the builder’s extensive supply chain, the custody of quality was left up to those consultants, often from a cost background, remaining by the client’s side.

The benefit was obvious: a contract could be signed – often much sooner than would previously been possible – and the cost was fixed, with the risk of cost overruns now the responsibility of the contractor. It was up to the builder how to deliver the project within the sum agreed and any unexpected increases would be down them to resolve. This arrangement was so compelling it became the default choice for most public sector projects of any significance. The inevitable consequence was, however, that contractors would look to save money within the parameters laid down by the contract information in the desperate hope of widening excruciatingly narrow margins. Something had to give, and the sacrifice was quality.

There’s a perception in some sectors that our obsession with quality is simply a demonstration of our detachment from the realities of modern contracting. Why spend £50 on a tap when we could spend £500 and have it in gold? This is nonsense, of course. Our concern extends not only to the needs of the commissioning client but also those who will ultimately occupy those buildings we design; rarely are these the same, particularly in the public sphere.

We care about the contribution our buildings make to wider society; the effect on those who live and work around them, too. We understand that decisions made during the design stage can have a profound effect on longevity, enjoyment and quality of life. Quality extends not only to the thoughtfulness of a building’s design, the selection of materials and how they are put together, but to the enjoyment of those that live, love, work and sometimes die in it.

The impact our buildings have on the lives of the people that inhabit them can be profound and success cannot simply be assessed on the day the building is handed over, but only after months, years or even decades have passed. Architects understand that the construction process itself is only a brief excursion within a far greater journey. By retaking our position at the heart of the process, we can concentrate our efforts on arriving at the right destination.

This article was originally published in PBC Today and was quoted in the BSR (Bereaved, Survivors and Residents) Group’s submission of evidence to the Grenfell Tower Public Inquiry.


After Grenfell

Passengers touching down at London City Airport are likely unaware that buried beneath the tarmac lie the brayed concrete remains of a 22-storey tower, the demolition of which signified a watershed moment in British housing. Erected hastily towards the end of the 1960s, Ronan Point concluded two decades of rapid housebuilding. At its peak, some 400,000 homes were completed annually, and in the fervour to replace the bomb-damaged slums of Victorian London it was perhaps inevitable there would be compromises in quality, with budgetary constraints eclipsing architectural ambitions and social concerns.

It was remarkable that on that spring morning of May 1968 so few people lost their lives. A gas explosion in a kitchen on the 18th floor blew out a load-bearing panel, which led to a collapse of one corner of the building, killing four. Although it stood for nearly 20 more years, Ronan Point was eventually pulled down in 1986, along with a number of other blocks built using the same construction methods, and deposited under the nearby airport runway.

This notorious event had two important outcomes, the effects of which we are still feeling today. The first was a comprehensive review of the Building Regulations — the statutory instrument that determines a building’s suitability for habitation — which were revised to outlaw the form of construction that enabled the ‘disproportionate collapse’ of the east London block. Secondly, it signalled an end to the British love affair with tower blocks and the modernist utopian dream. By the late 1970s we were building hardly any residential towers at all.

Fifty years on, the housing crisis of the early 21st century has reacquainted London with the concept of high-rise living. Inflating land prices have meant that developers wring every last square foot of space from tiny patches of brownfield land scattered across the city. Many of those towers that survived the purge of the 1970s and 80s, previously decried as failed social experiments, have been snapped up by canny developers and rebranded as desirable places to live: ‘luxury flats’ in convenient, accessible locations. Towers that remained in public ownership underwent less glamorous refurbishment through the Decent Homes programme, announced by the then deputy prime minister John Prescott at the turn of the new century. This ambitious initiative demanded that, within a decade, all social housing achieve minimum levels of quality. Often this work included the replacement of kitchens and bathrooms; in some cases upgrades to windows, thermal insulation and cladding to ‘spruce up’ ageing concrete.

Much of this work was carried out by a cabal of large construction companies who had become adept at offering councils a ‘one-stop shop’ of design and delivery, shielding the client from the risk of cost and programme overruns. Public clients, recoiling in paroxysms of fear at the prospect of capital projects running over budget, embraced this approach, taking comfort in the fact that fixed-price contracts would prevent costs unexpectedly spiralling out of control. As with the housebuilding boom of the late 1960s, the ambition of this new programme meant that design quality was sometimes of secondary importance to the need to deliver desperately needed new homes on time and within budget.

A consequence of this approach was the gradual excision of the architect from the construction process. The profession became seen as contributing little other than cost and complication, and its responsibility withered away to a point where it was seen as useful only for picking colours of cladding and helping to navigate tricky planning committees. Its technical expertise, pursuit of quality and consideration for those affected by the work became of secondary importance – an inconvenience that the budget and programme could ill afford. Rather than working directly for public clients, the design team began to work instead for main contractors, isolating architects yet further from the communities they were supposed to serve.

Just a few short weeks on from the Grenfell Tower catastrophe, it’s still too early to speculate as to why the fire spread with such terrifying rapidity. It may be that a particular configuration of standard building components contributed to the spread of flame across the outer skin of the building. Quite why in this case a small domestic blaze – of which there are many hundreds each year within tall residential buildings – led to so many deaths may take many months to determine.

It’s also impossible to say whether more meaningful involvement from the architect could have mitigated the tragic effect of the Grenfell Tower fire, but it is apparent from other recent cases that their exclusion has allowed bad practice to seep unchecked into the construction process. The recent Cole Report into problems with a raft of contractor-led schools in Edinburgh identified poor construction and inadequate supervision as the principal reason for a large number of serious building failures. Architects used to serve a nobler cause; now they have little choice but to serve those who pay the bills.

In his riposte to the Prince of Wales’s withering criticism of the profession in 1984, ex-RIBA president Maxwell Hutchinson claimed that the failure at Ronan Point was not because architects were involved in the construction. It was because they were not. Can it really be the case, half a century on, that we are back where we started?

This article was originally published in Icon magazine.