Redefining the green belt: the rise of grey belt planning

What is the ‘grey belt’?

From humble beginnings as a few paragraphs of guidance developed by the Greater London Regional Planning Committee in 1935 - with the stated aim of reserving a supply of public open spaces - green belt planning policy has become almost sacrosanct. It has been perceived by many as the only protection preventing all of our open countryside from being turned into concrete. It’s no wonder then, that proposals to relax green belt protections have become increasingly politically difficult.

Rebadging parts of the green belt as grey belt was therefore, if nothing else, a clever rebrand, giving the impression of a pragmatic compromise which could address the housing crisis without removing environmental protections. The government conjured images of abandoned petrol stations, derelict industrial sites, and low-quality scrubland near motorways, arguing that these areas were inadvertently being afforded protections meant for ‘proper’ countryside.

Away from the soundbites, it’s fair to say that explaining exactly what grey belt is, and isn’t, for the purposes of deciding actual planning applications, proved more of a challenge than selling the concept. That said, the December 2024 iteration of the National Planning Policy Framework (NPPF) now defines it as:

‘…land in the Green Belt comprising previously developed land and/or any other land that, in either case, does not strongly contribute to any of purposes (a), (b), or (d) in paragraph 143. “Grey belt” excludes land where the application of the policies relating to the areas or assets in footnote 7 (other than Green Belt) would provide a strong reason for refusing or restricting development.’

Three of the five purposes of the green belt referred to within the definition are:

• to check the unrestricted sprawl of large built-up areas;
• to prevent neighbouring towns merging into one another; and
• to preserve the setting and special character of historic towns.

This means that sites within the green belt which make only a limited contribution to these objectives, excluding areas or assets of particular importance (i.e., land with an existing environmental designation), may constitute the grey belt.

It may sound simple, but evaluating individual planning applications against these broad strategic objectives is easier said than done; often involving a complex exercise of planning judgment and interpretation. The introduction of Planning Practice Guidance (PPG) goes some way to explaining how this assessment should be approached and the reality is that the planning system and those who work within it are well versed in interpreting and applying this type of policy. That said, criticisms that the policy is over-complicated are not entirely without justification.

The effect on grey belt designation for decision making

National planning policy has long deemed development in the green belt to be inappropriate and harmful by definition, subject to specified exceptions for particular forms of development, such as buildings for forestry and agriculture or the provision of sporting facilities.

If planning permission is to be granted, inappropriate development must be justified by ‘very special circumstances’ which ‘clearly’ outweigh both the definitional harm caused by inappropriate development in the green belt and any additional harm specific to the proposed scheme. It’s a high hurdle and generally treated as such, particularly by planning committee members. 

Paragraph 155 of the NPPF now makes clear that development in the grey belt is not inappropriate where: 

• the development would utilise grey belt land and would not fundamentally undermine the purposes (taken together) of the remaining green belt across the area of the plan;
• there is a demonstrable unmet need for the type of development proposed;
• the development would be in a sustainable location, with particular reference to paragraphs 110 and 115 of this framework; and
• where applicable the development proposed meets the ‘golden rules’ requirements set out in paragraphs 156-157 below.

Where proposals satisfy these criteria, they are not classed as inappropriate for the purposes of green belt policy and do not have to overcome the high hurdle of demonstrating very special circumstances in order to secure planning consent. Better than that, in fact, the NPPF provides that developments that comply with the golden rules should be given significant weight in favour of the granting of permission. 

Thus, for schemes on grey belt land that comply with the golden rules, we’ve gone from a de facto presumption of refusal of planning permission to a presumption in favour of granting consent. 

The ‘golden rules’

To ensure that a major development on land released from the green belt benefits both communities and nature, the following requirements must be met:

• increased provision of affordable housing (for residential development);
• necessary improvements to local or national infrastructure; and
• the provision of new, or improvements to existing, green spaces that are accessible to the public.

In regard to affordable housing, proposals must reflect the relevant development plan policies produced in accordance with paragraphs 67-68 of the NPPF. If such policies have not been adopted then affordable housing provision should be 15% above the affordable housing requirement, which would otherwise apply to the development, subject to a cap of 50%. Where there is no pre-existing requirement, the default will be a 50% affordable housing provision.

Plan making

As well as affecting decisions relating to specific schemes, grey belt policy impacts the development of local plans. Local planning authorities must first look to release previously developed land, then undeveloped grey belt land, before considering the release of other green belt land. 

How is it working in practice?

Contrary to the House of Lords’ conclusion that the grey belt concept is largely redundant, the effects have been quick, immediate and significant.

We’ve seen a steady trickle of appeal decisions granting permission under this new grey belt policy. These have involved both housing and non-residential development, such as data centres and battery storage facilities, which would have previously needed to demonstrate very special circumstances in order to justify development in the green belt.

Planning consultancy, Marrons, has published research suggesting that the revised National Planning Policy Framework and grey belt policy could treble the number of acceptable sites considered for local plans. Its analysis reveals that 49% of all green belt planning appeals have been allowed between December and March this year, compared to 31% in a similar period in 2023-24. For housing appeals, 25% succeeded, up from 15% the year before.

Conclusion

There can be no doubt that the introduction of the grey belt marks a significant shift in green belt policy. Unlike some planning reforms, these changes have been introduced through policy rather than legislation, allowing the development industry to utilise them swiftly.

So, is it working? Well, that depends on your objectives. We are undoubtedly still in a ‘bedding in’ period, particularly in terms of establishing a consistent approach to how the policy is applied. That said, early decisions make it difficult to argue that the grey belt policy has not shifted the dial significantly in favour of development. Whether this relaxation of green belt orthodoxy heralds a wider rethink of how we approach it, amidst an acute housing crisis, remains to be seen.