Boris Johnson has been accused of repeatedly ignoring expert advice on the viability of his so-called vanity projects as London mayor, leaving taxpayers with a bill of nearly £1bn and rising.

Some of those who worked closely with Johnson as mayor, including fellow Conservatives, told the Guardian that he defied senior officials over a string of profligate projects and resisted being held to account for their ballooning costs.

The projects including going ahead with new Routemaster buses despite being told by his transport commissioner that they would be too expensive to run. He also purchased three secondhand water cannon against the advice of the lead police officer on riot control. And Johnson refused to publish the results of an 18-month study that he commissioned, after it unequivocally warned against his idea of building an airport in the Thames estuary.

Steve Norris, a former Conservative candidate for mayor and a board member of Transport for London, said Johnson’s record as mayor suggested he could be a “huge risk” as prime minister. “These projects tell us that Boris never reads the papers and isn’t great on detail,” Norris told the Guardian.

“He could be incredibly profligate for the country. He’s great on rhetoric but lousy on delivery.”

Johnson championed eight high-profile projects that either ended in failure or turned out to have questionable value. Between them they had cost the taxpayer £940m by 2017 and the price has since edged up still further. Earlier this year a TfL inquiry found that the final cost of garden bridge was £53.5m, £1.5m more than previously thought, of which £43m was public money. Costs included £417,000 on a gala for the abandoned project and £1.7m on salaries for the executives of the Garden Bridge Trust.

He could be incredibly profligate for the country Steve Norris, former Tory mayoral candidate

It has also since emerged that the Olympic Orbit tower and slide is £13m in debt with interest growing by £700,000 a year. Johnson commissioned the tower after bumping into the steel magnate Lakshmi Mittal at a cloakroom at the World Economic Forum at Davos, in an encounter that has already cost £6.1m.

The cost of the London stadium conversion soared to £323m, the bulk of which had to be paid by the taxpayer after protracted negotiations with West Ham United, the new tenants.

Johnson’s campaign did not respond to requests for comment. The Conservative leadership candidate has previously defended the projects as major contributions to the capital while his office has blamed the London stadium costs in particular on the previous Labour administration.

Andrew Boff, who served as Conservative London assembly member during Johnson’s tenure, said the mayor hated being questioned on the costs of such projects. “He looked throughly hurt whenever we would challenge him, as if he had been stabbed in the back,” he said.

Norris said Johnson should have stepped in earlier to stop the garden bridge project. “A great deal of money was wasted on the bridge and Boris has yet to acknowledge any role in that.”

But he claims the approval of new Routemaster buses, which was designed to meet Johnson’s manifesto pledge to bring back conductors on buses and allow passengers to hop on and off, was a “far more egregious error”.

Quick guide About this series Show Hide The real Boris Johnson Over the course of the week, the Guardian is publishing a series of news reports, features and multimedia components on the man widely expected to be the next Conservative leader – and therefore prime minister. In coverage that ranges from his early days as a journalist to his last senior job as foreign secretary, we will seek to shed light on the exploits, ambitions and values of one of the most consequential – and most divisive – politicians of the age.



He said: “I know Peter Hendy [TfL commissioner] said we couldn’t afford to run the buses with a separate conductor, but Boris decided to build them anyway.”

Hendy refused to comment about Johnson to the Guardian. In 2015 Johnson was forced to scrap conductors on the new Routemasters because they cost £62,000 per bus per year to operate.

The new Routemasters have also turned out to be less environmentally friendly than Johnson promised. New windows had to be fitted at an extra costs of £2m after temperatures of 38C were recorded on board. And this year 300 of the fleet of 1,000 have had to be upgraded to ensure they comply with the London’s low-emissions zone.

The total cost of the buses is put at £321.6m. Another major expense has been the “Boris bikes” cycle hire scheme, which was supposed to cost the public nothing but by last year had cost a cumulative £225m.

Earlier this year Johnson successor, Sadiq Khan, brought to an end another of Johnson’s failed projects when he sold for scrap three unusable second-hand water cannon at a net loss of more than £300,000.

The taxpayer could have been saved the bill if Johnson had listened to advice, according to Joanne McCartney, the current deputy mayor of London and assembly member under Johnson.

She said: “There was a report strongly recommending we should not buy them. We spoke to many people, including Sir Hugh Orde who had experience of using them in Northern Ireland, and was the Association of Chief Police Officer’s lead on riot control. [Johnson] didn’t even have the courtesy to read the report, subsequently he wasted hundreds of thousands taxpayer money.”

Environmental campaigners fear that as prime minister Johnson could revive the idea of putting an airport in the Thames estuary, a scheme he spent £5.2m exploring as mayor. David King, the former chief scientist, agreed to chair a commission on the idea despite his qualms.

King said Johnson first ignored his conditions for chairing the commission in a dishonest announcement to the press and then refused to publish its findings. “The gist of the conclusion was that it was not wise to put an airport in the Thames. It was unequivocal,” King said. He said his unpublished reported said that the airport would only be feasible if a new settlements were built around it.

It also found that the airport would have to sit high above the water to be safe from rising sea levels and tidal surges and the extra flights involved would be “very challenging” for air traffic control in the area.