Sir Sadiq Khan’s plans to “actively explore” building on some of London’s green belt in a bid to resolve the capital’s housing crisis has been welcomed as a major step in the right direction.

The mayor of London says existing rules prohibiting development on green belt land are simply unsustainable, given the surge in demand for housing in the city.

According to City Hall, around 88,000 new homes are needed annually for at least the next decade to meet demand.

“We have young professionals stuck in their childhood bedrooms for years on end, lifelong residents being priced out of their own neighbourhoods… primary schools closing because young families can’t afford local properties,” said the mayor.

“The damage the housing crisis causing is pervasive and profound.”

He explained: “City Hall’s new position is to actively explore the release of parts of London’s green belt for development.”

He said a large quantity of green belt land in London was “low-quality”, with only 13% of it being parkland accessible to the public.

“Given the quality of London’s green belt and the extent of London’s crisis, I believe the current position is wrong, out of date and simply unsustainable.

“Development in carefully chosen areas of the green belt, done in the right way would allow us to unlock hundreds of thousand of new homes.”

The government has welcomed the move, with Deputy Prime Minister Angela Rayner calling it a “bold proposal” that “rises to the challenge of tackling London’s housing crisis”.

Philip Allin, director, Boyer (London), is also among those to welcome Khan’s strategy.

He said: “The announcement by the mayor really has the potential to result in a significant step change in housing delivery, aligning with the approach now being taken elsewhere in the country. There are numerous examples of under performing Green Belt in highly accessible locations that could now come forward for development as a result of this change, particularly in the outer London Boroughs. The key will be ensuring that the benefits of doing so are clearly articulated and delivered with buy-in from the London Boroughs, something that is no doubt easier said than done.”

Sir Sadiq Khan’s commitment to ‘actively explore’ building on select Green Belt land represents a “significant and necessary step forward” in addressing London’s housing crisis, according to Sarah Hiscutt, partner in planning at Knight Frank.

She said: “At Knight Frank, we have long advocated for a balanced approach to Green Belt policy. A review of poorly performing undeveloped Green Belt land would serve to identify even greater opportunity beyond previously developed sites.

“According to our recent Residential Development Land Index Q1 2025 research, greenfield land values have edged lower, with housebuilders citing persistent cost inflation and planning uncertainty. The reality facing London is stark – delivering less than half of its 88,000 annual housing target while rents soared by 11.5% last year. Increased planning certainty through clear criteria for appropriate sites that are considered to be performing poorly would be beneficial despite cost inflation remaining high.

“Strategic green belt release would enable greater scope for suburban expansion, supporting the provision of family housing where it’s most needed and where supporting infrastructure is viable and can be efficiently extended. What’s essential now is establishing criteria for identifying appropriate sites and ensuring developments deliver substantial affordable housing, strong transport links, and enhanced public access to truly valuable green spaces.”