The London Assembly’s budget chair has thrown the gauntlet down over Boris Johnson’s decision to allow the historic London Fruit & Wool Exchange to be demolished.

John Biggs has tonight (Weds) announced he’s joining the 11th-hour heritage campaign to save the 1920s’ art deco building at Spitalfields, in the heart of his City & East London constituency.

The Mayor of London’s decision last week to approve its demolition—with only its facia remaining—has roused anger among campaigners after it had twice been rejected by Tower Hamlets council.

“The Fruit and Wool Exchange is part of the charm and heritage in this much-loved area of Spitalfields,” said Biggs.

“I am proud to add my support to the campaign to fight for this beautiful building which survived the Blitz.”

The development spells the end of the famous wartime air-raid shelter known as ‘Mickey’s Shelter,’ run by activist Mickey Davis who led a take-over of the reinforced basement in a challenge to the government at the height of the Blitz and turned it into a ‘people’s safety zone’ with its own social services.

Mickey’s Shelter became the model for all public shelters in London and forced a change of government policy over wartime public safety—campaigners say it should be turned into a permanent museum.

But all that will soon be swept aside, despite a long-running campaign by TV historian Dan Cruickshank who accused Boris Johnson of using autocratic powers against local democracy when he gave evidence at last Wednesday’s public hearing at City Hall.

Architect Paul Johnston put forward an alternative at the hearing on behalf of Cruickshank and the Spitalfields Community Group to show how the Fruit Exchange could be developed while preserving the character of the area.

He said: “London needs to show that it can sympathetically repair, regenerate and rebuild itself and not allow developers versed in bypassing planning policies to ignore the community and raze neighbourhoods.”

But the Mayor approved the plans for 100,000sq ft of offices and 10,000sq ft of retail units, using executive powers to ‘take over’ any strategic planning application.

John Biggs today accused the Mayor of “making a grave error in riding roughshod over people’s wishes.”

The redevelopment had been refused planning permission twice by Tower Hamlets council, in March and May.

The ‘Save Britain’s Heritage’ campaign and English Heritage had asked the government to ‘spot list’ the landmark earlier this month—but Boris Johnson went ahead with his executive decision to allow its demolition.