London mayor Sadiq Khan has vowed to make it significantly harder for property investors to convert small office spaces to residential use.

The pledge from the new mayor of London follows the publication of City Hall figures that suggest over 1.47m sqm office could already have been converted into residential units in the capital under permitted development rights since 2013.

Khan (pictured) claims that conversion on this scale could mean space for 93,750 jobs could be lost, based on a calculation that 16 sqm equates to one job, and as a consequence he has announced that he will amend the London Plan to provide stronger protection for small business and start-up workspace in the capital.

But the amendment could see Khan locked on a collision course with the government which views conversions of offices to residential as a key part of its pledge to develop 1m new homes by 2020.

Khan said: “Of course we need new homes, but this does not need to be at the expense of the space we need for the businesses that provide our jobs and drive our prosperity.

“Space which is genuinely surplus to commercial needs should be identified authoritatively and its release carefully managed so that it does not undermine local business.”