Dame Margaret Hodge, who carried out a review into the Garden Bridge, said today that she thought the controversial project would have ended up costing over £100m in public money had it gone ahead.
Speaking at a Greater London Authority Oversight Committee meeting, the Labour MP for Barking was asked what would have happened had the project continued.
She said: "I thought it would come to be over £100m of public money."
Hodge added that she came to that conclusion, having looked at the discussions she'd had with the Garden Bridge Trust, along with papers from the National Audit Office and the Treasury, but added: "I have to stress that is my own view."
The £200m plan to build the foliage-laden bridge over the River Thames was officially scrapped in August, but not before £37m of public money had been spent on the project without a spade going in the ground.
And according to the review carried out by Hodge, the agreement to underwrite cancellation costs by the government, could take the bill for taxpayers up to £46.4m.
"I felt why on earth didn't people engage more actively with the ordinary people? It was supposed to be the people's bridge, but I'm not sure which people it served," Hodge told the committee.
Asked what surprised her most after carrying out the review commissioned by London mayor Sadiq Khan, Hodge said the "total lack of regard for due process". She also cited "a real failure to engage effectively with people around, and garner support for the project".
Hodge said that the main difficulties facing the project "arose because of the lack of clarity about the purpose", which led to value for money concerns, as well as an issue around lack of transparency.
The Garden Bridge Trust said in August it had failed to raise necessary private funds after losing the support of Khan.
Chairman of the Garden Bridge Trust Lord Mervyn Davies said at the time: "It is with great regret that trustees have concluded that without mayoral support the project cannot be delivered."
In April,when Khan pulled the plug on support for the project after a report by the former chair of the Public Accounts Committee, Hodge said it was better value to write off the money already spent rather than continue with the project.
The mayor decided that continuing with the project would “expose the London taxpayer to additional financial risk”.
Questioned today on whether Hodge was friends with the mayor, she defended the independence of her review, saying: "I knew the mayor, he is a friend of mine, but that had absolutely no effect on the nature, the approach, or the conclusions of my report."