But Transport for London (TfL) and the Garden Bridge Trust have carried on regardless, egged on by powerful Bullingdon backers, mayor Boris Johnson and chancellor George Osborne.
The president of the Metropolitan Public Gardens Association has described it as a “vanity project of a windswept garden on an unneeded bridge”, while leading bridge engineers have called it a “private garden platform pretending to be a bridge”.
The National Audit Office has been ordered to examine the “rationale” behind George Osborne’s pledge of £30m of Treasury funding for the bridge.
Their correspondence over funding the bridge was recently uncovered by the Architects’ Journal, in which Osborne spelled out his £30m grant and urged Johnson to “do the same”.
Opponents have objected to the £60m of public funding and the £3.5m annual maintenance costs, to the restricted access for bikes and to the murky procurement process, which saw Thomas Heatherwick appointed ahead of other experienced bridge designers.