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

The London mayor should point out that the green belt is an anachronism and that a million homes could be built by sacrificing just 1 per cent of it.

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.