Data Centres Given Green Light on London’s Green Belt

For most of the past eighty years, a ring of land around London has carried a kind of protection that almost nothing else in British planning enjoys. The green belt survived housing shortages, population growth and decades of political pressure largely intact, because governments of every persuasion treated it as close to untouchable. That began to shift, at least on paper, on 16 July 2026, when the Mayor of London published the first draft of the new London Plan. Buried within it is a policy that gives data centres something no other major land use currently has, a standing route onto part of that protected land.

The concept dates back to 1955, when it was introduced as a tool to stop towns and cities sprawling into one another, not as a judgement on the ecological or scenic value of any particular field. As a result, London’s green belt contains a mixture of farmland, woodland, golf courses, disused sites and, in places, land that has already been built on or degraded in some way. Within this broader area sits a newer and more contested subcategory known as grey belt, which refers specifically to green belt land considered lower quality, previously developed, or of limited environmental and recreational value. It is this narrower category, not the green belt as a whole, that the new London Plan is proposing to open up.

The mechanism for doing so is a dedicated planning policy called GLE3, part of the Mayor’s broader Growing London’s Economy strategy. This matters because it marks the first time data centres have had a bespoke planning framework of their own, rather than being assessed under the same general rules that apply to warehousing and other industrial buildings. Under GLE3, data centres would be treated as, in the Mayor’s own phrase, the only exception to the usual restrictions on green belt development.

Green belt exceptions have historically been reserved almost exclusively for housing, and even then only in designated growth areas with strong transport connections. Data centres, by contrast, would gain a standing route onto qualifying grey belt sites outside those reviewed growth areas altogether, a route the plan explicitly states is not available to any other major use of land.

The justification offered for this distinction rests on how a data centre actually behaves once it is built. Officials argue that although these facilities can occupy large sites, they generate comparatively little daily traffic and require far fewer staff and deliveries once operational than a housing estate, a warehouse or a factory would. That is the basis on which the usual transport-link test, the one that has shaped where housing has been allowed to encroach on the green belt for decades, is being waived specifically for this sector.

It would be inaccurate to describe this as a blank cheque for developers, even if the practical effect still favours one industry over every other. The draft plan sets out specific conditions that a qualifying data centre must meet, built around energy and sustainability performance rather than the traffic and design tests that usually govern green belt exceptions. Proposals need to demonstrate a coordinated plan for recovering and reusing waste heat, measures to improve water and electricity efficiency, and, where feasible, on-site or nearby renewable electricity generation. 

In principle, this ties the exemption to a higher environmental bar than data centres faced when they were still assessed as ordinary industrial buildings. In practice, planning specialists have already described the overall approach as permissive, and green belt campaigners have gone further, warning that it risks setting a dangerous precedent for other sectors to argue for their own exceptions in future.

That warning is already playing out in Havering, in outer east London, where a proposed data centre campus at North Ockendon has become the first real test case of what this policy means on the ground. The scheme, which developers and the local council say could become one of the largest single data centre sites in Europe, is being promoted on the basis of roughly 1,240 jobs along with public benefits including a new heat network and an ecology park. Havering Council, acting as the local planning authority, has been consulting on the arrangements needed to bring the scheme forward, while residents’ groups and the local Member of Parliament, Andrew Rosindell, have raised concerns about both the pace of that consultation and the wider precedent of easing green belt rules for large-scale data centre development. Rosindell has been careful to say he is not opposed to data centres in principle, given how important the sector has become, but argues that growth should not come at the expense of countryside that local communities value.

Set against that backdrop, the housing comparison becomes hard to avoid. London’s housing shortage is genuinely severe, with the Centre for Policy Studies estimating a shortfall of around 1.1 million homes against the level of housing typical of comparable European cities. Yet analysis from the Centre for Cities has found that around nine in ten of the grey belt sites near London judged suitable for development already sit within green belt boundaries that housing has historically struggled to reach, precisely because most housing exceptions depend on proximity to public transport in a way this new data centre policy does not require. In other words, a sector facing far less acute pressure to expand into protected land than housing does has just been given an easier route onto it.

None of this means data centres are wrong to want the land, or that housing automatically deserves it more. Grey belt sites suitable for large-scale development are genuinely limited, and every hectare allocated to one purpose is a hectare that cannot be used for another. 

What the London Plan does is make an explicit choice about how to referee that competition. Data centres arrive with a strong case of their own, since they will employ hundreds of people, in a struggling labour market, bring substantial capital investment and business rates revenue, and sit within a sector the government has repeatedly identified as central to future economic growth. Housing carries an equally strong case, given a shortage now measured in the hundreds of thousands of homes across the capital. Faced with two choices, the plan resolves the tension by giving data centres a standing route onto grey belt sites that housing largely still lacks. That is not necessarily the wrong call, since land use decisions always involve trade-offs between competing goods, but it is a choice with a clear winner and a clear runner-up.

The stakes reach beyond London too. Roughly 80 percent of the UK’s operational data centre capacity currently sits in the capital, while some proposed sites elsewhere in the country have faced connection queues to the electricity grid stretching to fifteen years, so how London chooses to treat this sector could shape expectations nationally. 

Since taking office, Prime Minister Andy Burnham has signalled he wants to move away from what allies have described as an overly US-centric, unfettered approach to AI policy under the previous government, and reports suggest his team could reassess a range of related policies, including AI Growth Zones themselves. If London’s grey belt exemption proves successful in accelerating investment, it may become a template other regions look to adopt. If it becomes bogged down in legal challenges or public opposition, of the kind already building in Havering, it could just as easily become a cautionary tale that makes ministers more hesitant elsewhere. 

Either way, the question the North Ockendon dispute is really asking is whether Britain is comfortable giving one modern industry easier access to protected land than it has historically given to housing, despite housing facing the more acute shortage of the two.

None of this is decided yet. The consultation on the draft London Plan runs for three months, and the submissions made during that window, from councils, developers, campaign groups and ordinary residents, will help determine whether preferential grey belt access for data centres becomes a lasting feature of how Britain manages competing claims on protected land, or whether it remains a narrow, sector-specific exception confined to this one plan.

Do you believe the potential upside of accelerating Britain’s AI growth is cause enough to grant data centres this unprecedented access, and on what grounds would you defend that choice to someone who disagreed with you?

Green belt – A planning designation introduced in 1955 to stop urban areas sprawling into one another. It is a policy boundary rather than a measure of a site’s ecological or scenic quality.

Grey belt – A newer, more contested subcategory of land that technically sits within the green belt but is regarded as lower quality, previously developed, or of limited environmental and recreational value. It is grey belt land specifically, not the green belt as a whole, that the new London Plan proposes to open up to data centres.

GLE3 (Growing London’s Economy 3) – The dedicated planning policy in the draft London Plan that sets out how data centres will be treated.

AI Growth Zones – A national government framework designating specific areas of the UK for accelerated AI and data centre investment.

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Featured Image: Google data centre in Council Bluffs, IA — Wikimedia Commons