Boris Johnson could be investigated for misconduct in public office if it is shown that political pressure from him while London mayor played a role in the loss of more than £40m of public money on the city’s abandoned garden bridge, a senior lawyer has said.

Labour and the Liberal Democrats also said Johnson should face scrutiny over his role in a project he strongly supported, and which an earlier inquiry concluded was driven more by political considerations than value for money.

The foreign secretary, whose mayoral term ended in May 2016, is due to give evidence to a London assembly committee on Thursday, the first time he will face detailed questions on how £46.4m of public money was spent on a project of questionable value on which construction work never even began.



Touted by Johnson as an oasis over the Thames, the planned pedestrian link from Temple to the South Bank was scrapped in August last year because of a shortfall in funds raised by the charity behind it and a lack of final planning consent despite three years of talks.

The public liabilities, initially capped at £16m, had escalated by 2016 when Transport for London and the Department for Transport agreed to release funding for a construction contract, even though it appeared the stipulated conditions were not in place for this to happen.

Johnson is expected to face questioning from the committee as to whether he played any role in seeking the release of the extra money.

An artist’s illustration of the bridge Photograph: AFP/Getty Images

Kerry Underwood, a senior partner at Underwoods solicitors and a former judge, said a case under misconduct in public office could be considered if the actions of a public officer, such as a mayor, showed “reckless indifference” even if there was no dishonesty involved.

“Boris Johnson is giving evidence to the London assembly on Thursday, and if his appearance gives rise to any fresh evidence pointing towards him pushing through the construction money, then it may be that there is a case for the Crown Prosecution Service to look into the matter,” he said.



Misconduct in public office is a criminal offence under common law, which penalises official wrongdoing that can be deliberate, deceitful or simply amount to excessive neglect of duty.

About 100 cases reach the courts each year, but it is known as a complex area to prosecute. The Law Commission is carrying out a review of how well it works.

The shadow communities secretary, Andrew Gwynne, said Johnson needed to explain “why this project was allowed to spiral out of control”.



He said: “Boris Johnson drove forward this project during his mayoralty, and he needs to needs to provide answers on the role he and his office played in the reckless decision to release public funds for the construction contract.”



The Liberal Democrat leader, Vince Cable, said: “Boris Johnson must be pushed to explain his full involvement and actions in the garden bridge debacle. If it is found he was negligent in any way, action must be taken.”

Johnson has already faced criticism over the the project, which was first proposed by the actor Joanna Lumley, a family friend of Johnson.

A total of £60m of public money was committed, and £37.4m was spent by the Garden Bridge Trust, the charity behind the project, without any construction work being done.

A report by the Labour MP Margaret Hodge, commissioned by Johnson’s successor as mayor, Sadiq Khan, said the final total in public spending, with cancellation costs, was likely to reach £46.4m.

In a damning verdict on the bridge, which was designed by Thomas Heatherwick, she said the business case was always weak, and it had been “driven by electoral cycles rather than value for money”.

Johnson’s staff did not respond to requests for comment.