The Garden Bridge suffered a major blow today after London Mayor Sadiq Khan withdrew further Mayoral guarantees for the project.
In a letter to the chairman of the Garden Bridge Trust today – his formal response to Dame Margaret Hodge’s official review, - Khan said "it does not seem reasonable to me" that the trust would overcome its many obstacles before planning permission expires in December.
He said Dame Margaret "was right to conclude that the project progressing would expose the London taxpayer to additional financial risk, both with regard to the bridge's construction and its maintenance.
"I have been clear this should not be allowed to happen," Sadiq Khan said.
Khan previously supported the project as so much public money had been spent on it already, but in his letter he highlighted the Trust’s "lack of progress" on raising capital funds from private sources.
Since the trust was established three years ago it has secured £69m in pledges from private sources, but this has dropped from £85m in spring of 2015, leaving a gap of more than £70m still to find for a project whose projected costs have topped £200m.
Khan said fact that pledged funds were lower than two years ago "strongly suggests that support for this project is not robust enough to generate the required funds" and he cast doubt on the trust’s ability to raise the endowment funds needed to properly maintain the bridge.
A suggestion by the trust that starting construction would help draw in money was flawed, he said, and pointed out that if the project halted halfway, the costs of either completion or demolition would fall to the Greater London Authority.
Providing mayoral guarantees "will expose the London taxpayer to too much additional financial risk," he added.
Garden Bridge Trust chairman Lord Mervyn Davies questioned the validity of the evidence Dame Margaret used in her review, and wrote to her to "register concerns" earlier this month.
The Department for Transport and TfL have already contributed £30m, which they may need to write off.