New analysis from planning, design and development consultancy Marrons shows that grey belt policy continues to have a major impact on housing planning permissions, with 76% of major residential appeals approved since the policy’s introduction in December 2024.
The study reviewed all 224 planning appeals referencing “grey belt” between 12 December 2024 and 28 February 2026.
The headline finding shows that 19 of 25 major residential schemes – defined as developments of 10 or more dwellings – were allowed by the Planning Inspectorate.
The most common residential grey belt appeal size is between two and nine dwellings, with 22 out of 73 schemes gaining approval.
Overall, 49 of 112 residential grey belt appeals were allowed, equating to a success rate of 44%. Major housing schemes make up 22% of total residential grey belt appeals and 39% of approved residential schemes.
The data also highlights a clear pattern – the larger the site, the more likely it is to gain approval. Developments of 200 or more dwellings were all approved, those with 100-199 dwellings achieved a 75% success rate, 50-99 dwellings were 100% approved, and 20-49 dwellings saw a 67% approval rate.
Compared with Marrons’ previous analysis – which was directly cited in the government’s Autumn Budget (October 2025) – covering the period to 31 August 2025, the success rate for major residential appeals has dipped slightly from 80% to 76%.
Across all the 224 grey belt appeals (comprising all land uses), 50% have been allowed – rising to 53% when including the part allowed, part dismissed decisions as allowed – down from 57% previously, with residential schemes now making up 50% of appeals compared to 73% in the earlier period.
Non-residential appeals were split across a range of uses, including caravan and traveller sites (19%), energy projects (11%), and commercial and industrial developments (5% each), as well as smaller proportions of sui generis (4%), leisure (3%), retail (2%), education (1%) and healthcare (1%) schemes.
Regionally, the South East remains the primary hotspot, accounting for 35% of appeals, though its dominance has declined from 52%. The East of England now represents 26% of appeals, with the West Midlands and North West each at 11% – reflecting a wider geographical spread of grey belt activity.
Roland Brass, planning director at Marrons, said:
“Grey belt policy continues to be a game changer for achieving major residential planning permissions.
“The data shows that larger sites in particular are much more likely to succeed, which is crucial for unlocking the scale of development we need to address the housing crisis.
“While the overall proportion of major residential appeals allowed has dipped slightly since our last report, the policy is still performing and creating new opportunities across the country in sustainable and logical locations where there is a need for new homes.
“It is also important to acknowledge that more major schemes are being granted planning permission locally and this impacts on the number of appeals.
“However, given the number of planning applications that have been submitted over the past six months we expect overall numbers – for both local decision and appeals – to increase over the next year, particularly with the new National Planning Policy Framework (NPPF).
“Importantly, grey belt policy is not just about housing; it is also supporting a range of land uses including commercial, infrastructure, energy and community projects, which provide benefits to local areas.
“Grey belt policy has helped these schemes come forward and it is important for the industry to showcase the benefits of this policy, which is also protecting the most valuable parts of the Green Belt.
“It proves that well-constructed, straightforward policy interventions can have a real, immediate and positive impact on the planning system, helping to make it faster, simpler and more certain.”
Introduced in the revised NPPF on 12 December 2024, grey belt designations identify lower-performing areas of Green Belt land that can be released for development where it is appropriate and delivers clear community benefits.
The policy provides a transparent and evidence-based route to planning approval, helping accelerate housing delivery while ensuring the protection of the most valuable Green Belt land.