Following the introduction of grey belt, 1 in 3 (36%) housing appeals on grey belt land have been approved and its usage has the potential to treble the number of ‘acceptable’ sites considered for local plans, analysis from planning experts at Marrons has revealed.
Following the publication of the revised National Planning Policy Framework (NPPF) in December 2024, which launched grey belt policy, almost half (49%) of all green belt planning appeals have been allowed, compared to just 31% in a similar period the year prior. Looking at housing appeals in isolation 25% have been successfully appealed, compared to just 15% the year prior.
The graph below shows decisions allowed between 12 December 2024 to 3 March 2025 for both green and grey belt applications, compared to green belt applications for the same length of time in the year prior. The analysis shows that 1 in 3 (36%) housing applications made on grey belt land were approved.
Historically, sites identified as ‘acceptable’ for consideration for development across the green belt were those that made a low or no contribution to the five green belt purposes.
The introduction of grey belt, however, is set to increase the number of ‘acceptable’ sites three-fold as the new definition (Annex 2 of the NPPF) requires only the testing of three of the five green belt purposes and the level of contribution should not be ‘strong’.
Analysis from Marrons of three independent green belt reviews, undertaken before grey belt policy was implemented, show that, on average, 15% of sites make a low or no contribution to the green belt purposes, as shown in the table below.
Under the new regime, whereby sites are deemed ‘acceptable’ if they offer moderate or low to no contribution, this skyrockets to more than 60%, meaning councils will have significantly more sites to consider in their local plans.
Roland Brass, planning director at Marrons, who led the analysis, said:
“While the policy is still new and emerging, grey belt is proving to be a gamechanger, and it is having a significant impact on planning applications and local plans.
“Our analysis of planning appeal decisions and councils’ green belt reviews, including the Government’s recently updated guidance on the green belt, shows that the assessment process has become more objective. However, in practice, it remains subjective, as each site is assessed on a case-by-case basis and as a result there has been the odd inconsistent decisions.
“We are also seeing planning officers and members become increasingly confident calling sites grey belt as some major housing applications have been granted planning permission at the local level.
“The appeal decisions highlight the importance of achieving the golden rules around provision of affordable housing, infrastructure and open space so the benefits of grey belt also support communities meet local needs. Agreeing with a council that a site is grey belt can now significantly help de-risk and speed up the planning process to achieve a consent.”