LONDON Mayor Boris Johnson was told yesterday to come clean over reports he flew to San Francisco at taxpayers’ expense to lobby for funding for a bridge before procurement began.

Garden Bridge, a proposed pedestrian bridge over the River Thames, has been dogged by controversy since the project’s inception.

This week it was reported in the Architects’ Journal that Mr Johnson flew to the US to lobby global computer giant Apple for sponsorship alongside architect Thomas Heatherwick — then vying for the contract to design the bridge — in February 2013.