ES News email The latest headlines in your inbox twice a day Monday - Friday plus breaking news updates Enter your email address Continue Please enter an email address Email address is invalid Fill out this field Email address is invalid You already have an account. Please log in Register with your social account or click here to log in I would like to receive lunchtime headlines Monday - Friday plus breaking news alerts, by email Update newsletter preferences

Boris Johnson is targeting hundreds of “lost sites” — ranging from disused hospitals to abandoned training centres — in an effort to accelerate the pace of housebuilding in London.

The Mayor believes tens of thousands of homes could be built on publicly owned plots of land and using derelict buildings no longer needed by Government departments and agencies, some of which have been redundant for decades.

But his officials say they face huge bureaucratic obstacles from public bodies such as the NHS despite the desperate shortage of homes in London, which has a population growing by 100,000 people a year.

Deputy Mayor for Housing Richard Blakeway said: “Our frustration is that there are public bodies, in particular the NHS, that are sitting on huge swathes of land but have little focus on bringing it forward for development. In our last review of what land might be available, the NHS did not even provide a return.”

Mr Blakeway said examples included St George’s Hospital in Hornchurch, which closed in 2012, Dulwich Hospital, empty since 2005, and Springfield Hospital in Barnes.

City Hall claims huge support from Downing Street and hopes that powers in the Government’s Infrastructure Bill, which is in the Lords, will speed up the release of public land to commercial house builders.

In the past, sales of public land have had to be transferred from agencies to their parent Whitehall department before being sold to local development bodies. The bill will cut out the departmental “middle man”.

However, a drafting error means that the scope of the bill does not include London, requiring an amendment.

Mr Johnson has set a target of 42,000 homes being built in London each year. In recent years only about half that number have been completed.

But he said: “Rapid redevelopment, regeneration and most importantly thousands of new homes for Londoners could be just around the corner given the necessary fast-tracking powers.”

He was speaking at a ground-breaking ceremony to mark the start of construction at the former Catford greyhound stadium, which spent a decade in public ownership after shutting in 2004 and is being turned into 600 homes including 173 for affordable rent and shared ownership.

The Mayor’s team are also drawing up a “Domesday Book” of all publicly owned assets in London.

Mr Blakeway said: “It’s unforgivable that many of these assets are lying idle. We need the structure in place in London so we can crack on.”