Total costs on the project have risen to over £700m

The boss of the Olympic Park has quit amid a row over the ballooning cost of converting the Olympic Stadium into a football ground for West Ham United.

David Edmonds, chairman of the London Legacy Development Corporation (LLDC), resigned two days after the mayor of London Sadiq Khan ordered an investigation into the stadium project’s overrunning costs.

It was revealed on Monday that the cost of conversion work - carried out by Balfour Beatty - had jumped a further £51m to over £320m.

The total cost of building the Olympic Stadium and subsequently turning it into West Ham’s new home has now topped £700m, triple the initial estimate.

Edmonds became chair of the LLDC last September, having been on the board of the body and its forerunner the Olympic Park Legacy Company since 2010.

He also chaired E20 LLP, the joint venture between Newham council and the LLDC responsible for converting the Olympic Stadium, now renamed the London Stadium.

David Goldstone, LLDC chief executive, said: “David has made an enormous contribution to the legacy of the London 2012 Games and he has helped to steer the organisation through some extremely challenging issues. We thank him for all his hard work and wish him well in the future.”

As part of the conversion works, Balfour Beatty had to rebuild large parts of the stadium structure, as well as redo foundations and piling in order to bear the strain of supporting the largest cantilevered roof in the world.

Speaking to Building in the summer, Edmonds admitted the conversion cost was “considerable”.

He added: “The roof cost a lot more than we thought, because once we started to do the designs for the cantilevered roof, we realised that more strengthening had to go in than originally expected. Secondly, the development and evolution of the retractable seating has also been more expensive. I don’t attempt to hide the fact it has cost a lot more than originally planned.”