Thousands of new homes in our back yards

More than a thousand new homes a year are being built in London's back gardens, new figures reveal today.

Developers can build on the land because back gardens count as previously developed and are therefore "brownfield" sites.

But opponents fear the resulting lack of grass and soil could make London more vulnerable to flooding because rainwater is stopped from soaking into the ground. This can cause subsidence, affecting a whole street's property prices.

Campaigners say gardens also provide vital green spaces for the city and have called on the Government to close the loophole.

The figures were released by the Green Party's Darren Johnson, who chairs the London Assembly's environment committee. Mr Johnson said: "I was shocked by the figures which show that permission is being given to build over a thousand new homes a year in London's back gardens.

"Records have only been kept since 2004/05, but since then the go-ahead has been given for 3,525 units to be built on gardens.

"We all know that there is a vital need for new housing in London, but garden-grabbing developments are not the way to deliver them.

"We must protect back gardens by re-designating them as greenfield - or even green belt or metropolitan open land," said Mr Johnson.

"This will allow councils to reject applications in back gardens, remove the temptation from home owners to sell their back gardens and force developers to make maximum use of truly brownfield land like disused former industrial sites and warehouses."

He added: "Londoners know that in a city like theirs, gardens provide vital green oases."

Concern has already been raised about the number of Londoners concreting over their front gardens.

With parking space in the capital at a premium, an estimated 12 square miles of front gardens are now under concrete, an area more than 22 times the size of Hyde Park.

The loss of green space means that rainwater runs into underground drains instead of being absorbed by the soil, putting extra pressure on London's inadequate Victorian sewerage and drainage system.

This could lead to more incidents of localised flooding and flash floods, which can send raw sewage into the Thames.