London’s mayor approved plans to build almost 700 homes on a former Royal Mail site yesterday, sparking anger from campaigners for affordable housing.

Boris Johnson said the scheme at Mount Pleasant was in danger of stalling, insisting that a number of affordable homes will be included.

But the local council, politicians and the main postal workers’ union all attacked the plans, saying just a quarter of the houses will be “affordable” — and even those will have rents twice the local rate for council or social housing.

Islington councillor James Murray said: “We need genuinely affordable housing in the capital, but today’s decision means that Londoners are missing out, while investors in luxury flats and Royal Mail shares are benefiting.

“The windfall to Royal Mail as a result of this planning application being approved is likely to be tens of millions, at the expense of affordable housing.”

Communication Workers Union general secretary Billy Hayes said: “London is in desperate need of truly affordable decent housing and Boris failed in his duty as mayor today by approving this planning application.

“Boris says he is committed to delivering affordable housing for Londoners, but he has no idea about what that actually means for people working in the capital

“It’s an absolute travesty that postmen and women working just next door will be priced out of this luxury development at Mount Pleasant.”

Labour London Assembly Member for Barnet and Camden Andrew Dismore added: “In just a few months, Royal Mail has gone from a public institution to a private company intent on selling off its assets with no regard for local communities.”