Rethinking London’s green belt: From constraint to critical infrastructure

For decades, green belt policy has largely been viewed through the lens of what development it prevents. But London’s future challenges suggest a different conversation is needed.

LUC has supported the Greater London Authority by producing evidence-based components to support the production of the new London Plan. Following the adoption of the new National Planning Policy Framework in 2024, updates to national green belt policy including the introduction of grey belt resulted in LUC being commissioned to undertake the first ever London-wide strategic green belt assessment.

LUC planners applied a robust approach to assess over 34,000 hectares of green belt land. The work confirmed significant variation in how green belt contributes to the green belt purposes, providing the first consistent picture of performance across London.

Alongside this, LUC has undertaken further green belt assessments to explore where development would result in fundamental harm and where enhancements would have the most multifunctional benefits for people and nature.

This work highlighted how the real value of London’s green belt land increasingly lies in what multifunctional land uses it delivers. Historically green belt has often been treated as a passive designation, but LUC work has increasingly highlighted how it performs essential functions that helps London respond to climate risk, nature and biodiversity recovery, flooding risk, urban heat effects, active travel provision and access to nature.

Although 20% of green belt across London was identified as provisional grey belt (almost 7,000 hectares), only 1% of this was not covered by a NPPF Footnote 7 designation – i.e. protected by an overlapping planning designation such as flood zones, conservation areas, or nature reserves.

This highlights the importance of reframing green belt as critical infrastructure for Londoners and this narrative immediately broadens the conversation beyond a planning story and creates a more compelling narrative for investment and enhancement. The areas of green belt that have been found to strongly perform against the green belt purposes should particularly be prioritised for investment so that future green belt discussions target public benefits and nature recovery.

This shift in perspective comes at a critical moment for London. With the new London Plan published for consultation, the capital faces growing pressure to deliver homes, support economic growth, improve climate resilience and reverse biodiversity decline. The challenge is therefore around how land can deliver multiple public benefits simultaneously

Perhaps one of the most significant outcomes of the London-wide assessment is the demonstration of the value of strategic planning. Challenges such as housing delivery, climate adaptation, green infrastructure provision and nature recovery do not stop at borough boundaries. By creating a consistent evidence base across London’s green belt, the assessment provides a framework for decision-making at a city-wide scale and helps support the development of a more coordinated spatial strategy for the capital.

One of the more important lessons emerging from the assessment is that land identified as making a weaker contribution to green belt purposes is not necessarily unused or without value. In many cases, areas identified as grey belt or weaker-performing green belt continue to provide important environmental, recreational, employment or infrastructure functions.

This reinforces the scale of London’s growth challenge. If substantial development needs cannot be met within existing urban capacity, the answer is unlikely to be found through a simple review of green belt boundaries alone. Instead, future planning may require a broader strategic conversation about growth across London’s wider geography.

Ultimately, the green belt debate has focused on boundaries for too long. As London plans for future growth, the more important question may be not how much green belt exists, but how effectively it works. By treating green belt as critical infrastructure rather than simply a planning designation, policymakers have an opportunity to secure multiple benefits for future generations while supporting a more resilient and sustainable London.