Key to the mayor’s vision are fewer expensive towers in central London and more affordable homes in the suburbs

Sadiq Khan

London mayor Sadiq Khan has launched a withering attack on the capital’s house builders and called for 65% of new homes being built to be set aside for affordable housing.

Khan said developers put up “too many luxury penthouses that only the very wealthiest investors can afford”, and needed to increase their annual current construction rate of 29,000 homes to 66,000, of which nearly two thirds should be designated ‘affordable’.

Key to Khan’s vision are fewer expensive tower blocks in central London and more affordable homes in the suburbs.

Last month Khan threw out an attempt by developers Squire & Partners to reduce the number of affordable apartments at its Scotland Yard project, a move which would have reduced the affordable housing quota on the site from 4% to 3%.

The mayor also took a swipe at his predecessor, Boris Johnson, whom he said had presided over a collapse in the number of homes built for social rent down to zero, and overseen the lowest number of affordable homes built since records began.

Khan told the Guardian the housing crisis was a major factor in the high cost of living in the capital, “as well as putting home ownership out of the reach of many young Londoners who fear they will never get a foot on the property ladder.

“In the worst cases, it can affect social cohesion, cause poor health and plunge residents into poverty. I cannot overestimate how terrible a situation we inherited.”

Khan had previously stated a goal of 50% of new developments should go to affordable housing, and doubts hover over the likelihood that his new target is achievable.

Responding to Khan’s call, a spokesman for the Housebuilders Federation said a “degree of flexibility” was needed when creating new affordable housing targets.

“In addition to new affordable homes, developments are also expected to deliver important local infrastructure, so compromises must be made if landowners are going to agree bring sites forward.

“The Mayor’s aspirations are welcome and we look forward to a bold and ambitious London Plan, but Londoners will want to know that proposals are realistic and workable.”

And Tamara Sandoul, policy manager at the Chartered Institute of Environmental Health, said Khan’s announcement was “much needed and timely”.

“London has some of the least affordable housing in the country and raising the target for affordable homes in the capital is a step in the right direction,” she added.

Sandoul also welcomed the mayor focussing on affordable rent schemes, which would “enable many young people to start saving for their deposit instead of the majority of income going on sky-high rents”.