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With an annual target of 88,000 new homes, London faces an ambitious goal, which has consistently proved difficult to meet. With the capital delivering less than half this target while rents soared by 11.5% last year, the reality is stark. The mayor's commissioning of a London-wide Green Belt review represents a change in strategic thinking about how the capital can respond to both national political directives and housing need.

We have long advocated for a balanced approach to Green Belt policy. Designation remains important, but it's clear that in some cases, particularly in the outer London boroughs and some suburban areas, particularly well contained or sustainable sites with previously developed or low-quality, isn鈥檛 performing as effectively as intended.

Opportunity among market pressures

Our Q1 Land Index shows a modest decline in greenfield land values, as housebuilders face rising costs and persistent planning uncertainty. Despite these headwinds, the current environment creates space for well-timed, strategic intervention. Providing more clarity in planning decisions and setting clear guidelines for suitable Green Belt development could help unlock opportunities in the months ahead.

The London Plan consultation has emphasised a brownfield-first approach, which remains the cornerstone of sustainable development. However, this must be complemented by unlocking transport infrastructure investment and appropriate incentives to encourage outer London boroughs to optimise traditionally lower-density brownfield sites. The reality is, viability challenges and building safety requirements have constrained delivery in zones 3 to 6, where growth would traditionally be expected.

This pressure has led developers to explore sites further out, making the mayor鈥檚 Green Belt review more timely. There's clear opportunity to review land previously constrained by Green Belt policy, bringing forward poorly performing land in a considered way that aligns with NPPF requirements.

The path forward: challenges & criteria 

Strategic Green Belt release and Grey Belt present enormous opportunity for London precisely because they haven't been attempted before at this scale. Green Belt has always been protected, off limits unless very special or exceptional circumstances could be demonstrated through local plan preparation or speculative planning applications. The mayor's identification of this as a critical growth opportunity signals a fundamental shift in strategic thinking.

That said, there are still some big hurdles to overcome. While the London Plan can point out areas where Green Belt land might be released, it doesn鈥檛 actually have the authority to allocate specific housing sites. That kind of decision needs close coordination between strategic planning and local policies.

This raises critical questions: how will local boroughs be incentivised to engage proactively with Green Belt release? How will they be supported to act on strategic guidance while meeting their own housing delivery targets? What interventions will be available in locations where there is disagreement in approach? Clarity around Grey Belt and its application in strategic policy will also be influential.

Not all London boroughs will play the same role, since central London has no Green Belt land at all. This adds another layer of complexity when it comes to rethinking housing targets and how they鈥檒l be delivered under this new strategy. The interaction between mayoral objectives and local authority capabilities will therefore be crucial to success.

Funding and affordable housing

Recent announcements on AH funding add context to this policy shift, offering opportunities for London boroughs to respond more effectively to overall housing needs particularly AH delivery.

National policy now mandates 50% AH on Green Belt and Grey Belt land without viability considerations, acknowledging the unique status of these protected areas. Where public benefit justifies releasing such land, developments must deliver both the quality and volume of housing Londoners urgently need. This principle is likely to influence London鈥檚 strategic policy, aligning with the mayor鈥檚 ambition to boost AH delivery though questions remain around how grant funding will support these new expectations.

Looking ahead

The Towards a New London Plan consultation closed on 22 June. The mayor has taken a proactive stance, inviting industry input on delivery challenges and opportunities. Reviewing the Green Belt will take time, it鈥檚 a complex process with no short-term answers.

For now, the focus must be on continued engagement with strategic policy development, monitoring Green Belt/Grey Belt policy changes, and ensuring appropriate sites are promoted through ongoing Local Plan consultation processes. The GLA's Land4LND programme (a call for sites exercise) provides a new digital tool for understanding strategic land availability in London, but sustained dialogue will be essential.

Having clear, consistent criteria for identifying appropriate sites will be key, ensuring developments deliver a solid amount of AH, strong public transport links, and enhanced access to green spaces. This represents both London's greatest housing opportunity and its most sensitive political challenge.

The mayor鈥檚 鈥渁ctive exploration鈥� of Green Belt isn鈥檛 just policy evolution it鈥檚 a recognition that London鈥檚 housing crisis requires bold, strategic action. Success will depend on aligning vision with local delivery, backed by clear frameworks and sufficient funding. The stakes are high but so is the opportunity.