Grey Belt and the New NPPF: What December 2024 Actually Changed

The December 2024 National Planning Policy Framework introduced "grey belt" into planning policy for the first time. After months of political discussion, the concept now has a formal definition and a policy framework. But the reality of what changed is more nuanced than either the celebratory or the alarmed headlines suggested.

This article explains what the December 2024 NPPF actually says about grey belt, how it interacts with the broader Green Belt framework, and what it means in practice for landowners, developers, and local authorities.

Grey belt is defined in the NPPF glossary (introduced December 2024) as land in the Green Belt that has been **previously developed** or that is not **strongly performing** against the purposes of the Green Belt as set out in paragraph 143. The purposes of Green Belt are well established: checking urban sprawl, preventing neighbouring towns from merging, safeguarding the countryside from encroachment, preserving the setting of historic towns, and assisting in urban regeneration.

The key word is "or" — grey belt land can qualify either because it is previously developed land (brownfield in the Green Belt) or because it does not strongly perform against the Green Belt purposes. This second limb is the significant one, because it opens up the possibility of development on greenfield land within the Green Belt that is assessed as making a limited contribution to Green Belt purposes.

NPPF paragraphs 154 and 155 set out the policy framework. Paragraph 154 states that when reviewing Green Belt boundaries, local authorities should give **first consideration to land that has been previously developed and/or land that is not strongly performing against the purposes of including land in the Green Belt**. Paragraph 155 clarifies that grey belt land should be prioritised for release when local authorities are redrawing boundaries through the plan-making process.

It is important to be clear about what grey belt does not do:

**Grey belt does not remove land from the Green Belt.** Land designated as grey belt remains in the Green Belt until it is formally released through the Local Plan process. The normal Green Belt policies — including the requirement for very special circumstances for inappropriate development — continue to apply to grey belt land until a Local Plan review removes it.

**Grey belt does not create an automatic right to develop.** The designation identifies land that should be prioritised for release, but the release must happen through the plan-making process with proper consultation, sustainability appraisal, and examination.

**Grey belt does not override other planning constraints.** Land may be grey belt and also affected by flood risk, heritage, ecology, or landscape constraints. Those constraints must still be assessed and addressed through the normal planning process.

The December 2024 NPPF also made significant changes to paragraph 11 — the tilted balance. Where a local authority cannot demonstrate a sufficient supply of housing land, the presumption in favour of sustainable development applies, and permission should be granted unless the adverse impacts significantly and demonstrably outweigh the benefits.

The interaction between grey belt and the tilted balance is where the real impact lies. For local authorities that cannot demonstrate a five-year housing land supply and have not engaged with Green Belt review through their Local Plan, the pressure to consider grey belt release is significant. The government's intention is clear: housing delivery should not be constrained by Green Belt land that is not strongly performing its Green Belt function.

The December 2024 NPPF also revised the standard method for calculating local housing need. The revised method produces higher housing figures for many authorities, particularly those in high-demand areas. This increases the gap between housing need and supply, which in turn increases the number of authorities that cannot demonstrate a five-year supply, which in turn triggers the tilted balance.

The combined effect of higher housing numbers, the tilted balance, and the grey belt framework creates a coherent (if politically contentious) policy direction: local authorities must plan for more housing, and if they do not, the framework provides mechanisms — including grey belt release — to deliver it.

The NPPF does not prescribe a methodology for assessing whether land is "strongly performing" against Green Belt purposes. This is deliberate — the assessment will be carried out through Green Belt reviews as part of the Local Plan process, using methodologies that are likely to vary between authorities.

However, the established Green Belt assessment methodology — typically assessing each parcel of Green Belt land against the five purposes, using a scoring system ranging from "strong" to "weak" contribution — provides the obvious framework. Land scoring "weak" or "limited" against the purposes is, by definition, grey belt under the NPPF definition.

Our analysis of existing Green Belt reviews across England shows that many authorities have already identified parcels of Green Belt land that make a limited contribution to Green Belt purposes. These existing assessments provide a ready-made evidence base for identifying grey belt land under the new framework.

For landowners with land in the Green Belt, the grey belt framework creates a new pathway — but not a shortcut. The key questions are:

**Is the land previously developed?** If so, it qualifies as grey belt and should be prioritised for release in the next Local Plan review.

**Does the land strongly perform against Green Belt purposes?** If not, it may qualify as grey belt. This assessment requires professional judgement and evidence — typically a Green Belt purpose assessment against the five paragraph 143 purposes.

**Is the local authority reviewing its Local Plan?** Grey belt release happens through the plan-making process. If the authority is in the early stages of a Local Plan review, there may be an opportunity to promote grey belt land for allocation.

**Can the development deliver the golden rules?** NPPF paragraph 155 (December 2024) sets three golden rules for major schemes on grey belt land: affordable housing at 15 percentage points above the highest applicable local plan target capped at a maximum of 50%; necessary infrastructure improvements proportionate to scheme scale; and accessible new or improved green spaces. These requirements are higher than typical policy requirements and must be factored into viability assessments. The earlier draft Working Paper proposed a flat 50% affordable housing rule; the final NPPF replaced that with the +15 percentage points formula.

In the months since December 2024, several local authorities have begun incorporating grey belt assessments into their emerging Local Plans. Some authorities that had stalled their Green Belt reviews have restarted them. A small number of appeal decisions have begun to reference grey belt in their reasoning, although the case law is still in its infancy.

The practical impact will depend on how quickly authorities adopt the framework, how robustly they assess Green Belt performance, and whether the "golden rules" for grey belt development prove deliverable in viability terms. The affordable housing requirement (+15 percentage points above the local target, capped at 50%) will be tested against site-specific viability in many locations.

Grey belt is a meaningful policy change, but it is evolutionary rather than revolutionary. It formalises an approach that many authorities were already taking through Green Belt reviews and provides a policy hook for prioritising the release of poorly performing Green Belt land.

For developers and landowners, the key message is that grey belt creates an opportunity through the plan-making process — not a bypass around it. The sites that will benefit most are previously developed sites in the Green Belt and greenfield sites that demonstrably do not serve Green Belt purposes, where there is a willing local authority engaging with its Local Plan.

Understanding the new framework — and being able to demonstrate where land sits within it — is now an essential part of land promotion in Green Belt areas.