BLOGS

Introduction

When the revised National Planning Policy Framework landed in December 2024, ministers were at pains to reassure the public: grey belt meant "disused petrol stations" and "abandoned car parks" — the scrubby, unloved fringes of our towns. Development would be targeted and proportionate, they promised, with strict "golden rules" to ensure 50% affordable housing and genuine community benefit.

Eighteen months later, the grey belt has become one of the most contested concepts in British planning. Approval rates have surged, planning applications are up sharply, and local authorities are scrambling to update their local plans before mandatory deadlines. Yet campaigners argue the policy has morphed into something far broader than voters were led to expect, with productive farmland and wildlife sites now routinely classified as developable grey belt.

REalyse planning data and recent policy research paint a picture of a system in flux — one where the gap between political rhetoric and planning reality grows wider by the month.

The numbers tell the story: approval rates climb as definitions stretch

REalyse analysis of residential planning applications shows a marked acceleration since the grey belt policy took effect. Approval rates for residential schemes have climbed from around 31% in mid-2023 to over 70% by early 2026, with some months exceeding 75%. The total residential units entering the pipeline have averaged over 40,000 per month, with periodic spikes exceeding 50,000 units.

This shift is most pronounced in areas under acute housing pressure. Central London leads with over 4,100 applications in the past two years, followed by Greater Manchester, the West Midlands, Kent, and Essex. Scottish regions such as Strathclyde show approval rates above 85%, while some outer London boroughs like Croydon and Redbridge remain below 35% — reflecting both local politics and the uneven application of grey belt criteria.

The government's own figures suggest planning applications for 335,000 homes were lodged outside London in 2025, a 60% increase on the previous year. Dwelling starts rose 23% in Q4 2025 compared to Q3 — the strongest quarterly increase since the post-pandemic recovery.

Yet the composition of these approvals has alarmed countryside campaigners. Research from CPRE, the countryside charity, found that 88% of homes approved on grey belt land since December 2024 will be built on previously undeveloped countryside — not the brownfield scraps the public was promised. In Hertfordshire alone, 89% of Green Belt planning applications last year invoked grey belt classification, affecting more than 200 hectares in St Albans district — equivalent to over 300 football pitches of open land.

Political battles intensify as local plans face deadlines

The grey belt policy has ignited fierce political debates at both local and national level. Local authorities now face a 12-week deadline from December 2024 to commit to updating their local plans, with the new requirements enforced from March 2025. Councils that fail to demonstrate a six-year housing land supply (increased from five years for older plans) will find themselves vulnerable to speculative applications.

A £14.8 million government fund has been established to help councils undertake Green Belt reviews and update local plans, but the capacity challenge is real. The Planning and Infrastructure Act 2025 allocated £48 million to recruit approximately 1,400 new planning officers — nearly five times the original manifesto commitment — yet skills shortages remain acute.

The political pressure is building from multiple directions. In London, Mayor Sadiq Khan has announced plans to allow strategic Green Belt release, arguing the capital needs one million homes over the next decade and that brownfield alone cannot deliver them. His consultation on the next London Plan will shape development patterns for 20–25 years.

Meanwhile, CPRE's petition against the grey belt definition gathered over 42,000 signatures, and the charity has submitted objections on 48 planning applications across Hertfordshire where grey belt justification was invoked. A House of Lords inquiry described the policy as "implemented in a somewhat rushed and incoherent manner" and unlikely to have "any significant or lasting impact" on meeting housing targets.

The 50% affordable housing requirement on grey belt sites — one of the golden rules — has itself become contentious. While intended to ensure public benefit, developers argue the mandate creates viability challenges that could deter investment, particularly on sites with infrastructure costs or remediation needs.

The pipeline paradox: 1.4 million homes already permitted but unbuilt

Perhaps the most uncomfortable finding for grey belt advocates is that over 1.4 million homes with planning permission granted since 2017 remain unbuilt. CPRE research suggests a comparable number could be accommodated on genuinely previously developed brownfield land.

This raises a fundamental question: is Green Belt release truly necessary, or is the housing crisis primarily a delivery problem rather than a land supply problem?

REalyse data on the planning pipeline shows significant volumes of approved but unstarted schemes across the country. The gap between permissions and completions reflects a complex mix of factors: developer viability assessments, build-out rates constrained by sales absorption, infrastructure capacity, and the skills shortage that leaves the construction sector more than 150,000 workers short of requirements.

The government's response has been to attack the problem on multiple fronts: planning reform to speed approvals, grey belt release to expand land supply, £625 million for construction skills training, and tougher accountability for developers who bank permissions without building. Whether these interventions prove sufficient to deliver 370,000 homes annually — a rate not seen since 1969 — remains uncertain.

What grey belt means for investors and developers

For property investors and developers, the grey belt policy creates both opportunities and risks. Sites that were previously protected may now be viable for housing, particularly in commuter corridors with strong transport links. REalyse planning data shows particular strength in growth areas like Milton Keynes, Central Bedfordshire, and South Cambridgeshire — precisely the locations prioritised under new station-adjacent densification policies.

However, the golden rules impose significant obligations. The 50% affordable housing requirement, combined with infrastructure contributions and biodiversity net gain obligations, will squeeze margins on many sites. Developers will need robust viability analysis and early engagement with local authorities to navigate the new landscape.

The subjective nature of grey belt classification also creates uncertainty. What constitutes land that "does not strongly contribute" to Green Belt purposes is open to interpretation, and local authorities may apply the criteria inconsistently. Sites that one council deems grey belt may be treated as protected Green Belt by another, creating an uneven playing field across regions.

For investors monitoring development pipelines, understanding which local authorities are actively reviewing their Green Belt boundaries — and which are resisting — will be critical. REalyse tracking of planning applications, approval rates, and local plan progress can provide early signals of where opportunities are emerging and where political resistance may stall development.

Conclusion

The grey belt policy represents the most significant intervention in Green Belt protection since the designation was first introduced. Whether it proves to be a pragmatic compromise that unlocks desperately needed housing, or a developers' charter that erodes countryside protections by stealth, depends largely on how local authorities and planning inspectors apply the deliberately flexible definitions.

What is clear from the data is that the planning system is already responding. Approval rates are up, application volumes are rising, and housing starts have begun to recover. Yet the gap between permissions and completions remains stubbornly wide, and the construction industry faces fundamental capacity constraints that planning reform alone cannot solve.

For the government's 1.5 million homes pledge to succeed, grey belt release will need to be one tool among many — complemented by brownfield regeneration, new towns, skills investment, and genuine accountability for build-out rates. The political battles over Green Belt will only intensify as more sites are classified as grey, and the definition's ambiguity ensures that courtrooms and planning inquiries will be kept busy for years to come.