The line-by-line account of their spending reveals £161,000 spent on their website and £400,000 on a gala fundraising event, amongst many other eyebrow-raising numbers. 

Bear in mind that back in 2012, Johnson promised that the bridge would be entirely privately funded. The bridge’s most ardent advocate, Joanna Lumley, called it a “tiara for the Thames” and “a gift for London”. Today, the project would seem the very opposite of a “gift”.

The London Assembly has been scrutinising this project since its inception, and I now chair a working group tasked with continuing our investigation. We are indebted to the work of local campaigners around Waterloo as well as Will Hurst of the Architects Journal, who has brought many of the scandals surrounding the project into the open, and who was the subject of an extraordinary public attack by Johnson for doing so.

Yet every revelation about this cursed project has thrown up more questions than it has answers, and it’s worth reminding ourselves just how shady and rotten the story of this project has been.

There was Johnson’s £10,000 taxpayer-funded trip to San Francisco to drum up sponsorship for the Thomas Heatherwick garden bridge design, despite the fact that TfL had not at that point even tendered for a designer for the project.

The design contest itself was a sham, with one of the two other architects TfL begging to enter in an attempt to create the illusion of due process later saying they felt “used”. Heatherwick Studios was awarded the contract and made a total of £2.7m from taxpayers from the failed project.

London’s Garden Bridge: where did it all go wrong?

Soon after the bridge’s engineering contract had been awarded to Arup, it was announced that TfL’s then-managing director of planning, Richard de Cani, was departing TfL for a new job – at Arup. He continued to make key decisions relating to the project while working his notice period, a flagrant conflict of interest that wouldn’t have been allowed in the civil service. Arup received more than £13m of taxpayer cash from the failed project.

The tendering process attracted such concern that the then Transport Commissioner, Peter Hendy, ordered an internal audit of it. The resulting report was a whitewash, and a far more critical earlier draft was leaked to the London Assembly.

As concerns about the project grew, so did the interventions by the bridge’s powerful advocates to keep it on track. Boris Johnson signed a mayoral direction which watered down the conditions the Garden Bridge Trust had to meet in order to gain access to further public money, exposing taxpayers to further risk. When he was hauled in front of the London Assembly to explain this decision, after blustering for while he finally told me that he couldn’t remember.

David Cameron overruled the advice of senior civil servants in order to extend the project’s government credit line. And George Osborne was at one point even more keen on the Garden Bridge than Johnson himself. The then chancellor was criticised by the National Audit Office for bypassing usual channels in order to commit funding to it. Strangely, none of the project’s travails have made it onto the pages of the London Evening Standard, a paper he now edits. Nor did they under his predecessor Sarah Sands, now editor of the Today Programme, another firm advocate for the Garden Bridge.

By 2016 the project appeared to be in real trouble. Yet the Garden Bridge Trust ploughed ahead in the face of mounting risks. In February 2016, despite having not secured the land on the south bank to actually build the bridge on, nor satisfied all their planning consents, the Trust signed an engineering contract. That decision alone has cost the taxpayer £21m.

Minutes of the Trust’s board meetings that I secured from TfL (after much wailing and gnashing of teeth from the Trust itself) reveal that weeks beforehand Thomas Heatherwick had urged the trustees to sign the contract in order to demonstrate “momentum”.

Meanwhile, TfL, which was represented at board meetings by Richard de Cani and so should’ve been well aware of the mounting risks to the project, astonishingly failed to act in interests of taxpayers by shutting the project down.

Indeed, TfL allowed further public money to be released for the project despite the Trust not having satisfied at least two of the six conditions that had been set by TfL in order to protect the public purse. The decision to approve funding was personally approved by Transport Commissioner Mike Brown, who has never provided an adequate explanation for his decision.

The story of the Garden Bridge project is one of incompetence, arrogance and recklessness, but also of privilege and power. This was “the great and the good” trying to rig the system to force upon London a plaything for themselves wrapped up as a gift.

The London Assembly is determined to hold those responsible to account, and we will particularly focus on TfL’s role in this mess. However, this is not just a London issue, but a national scandal. There is a growing case for a Parliamentary inquiry into the project, and I would urge the Public Accounts Committee to launch an investigation. 

The Garden Bridge may seem like small beer compared to Brexit. But there is a common thread: Boris Johnson. It should appal and outrage us that this man is still being talked about as a potential future Prime Minister. His most expensive vanity project, now dead in the water, perhaps serves as an unwelcome prophecy for what may be to come should he ever enter Number 10.