A major west London regeneration project backed by the Mayor of London has admitted giving false information in its bid for £250 million from Government.

The Old Oak Park Development Corporation (OPDC) is the UK’s biggest housing development – it aims to bring 25,500 homes and 65,000 jobs to Park Royal.

But the project – started by Boris Johnson while he was Mayor, and now supported by Sadiq Khan – has struggled to make headway with its home-building ambitions.

Now documentation made public following a legal order from the London Assembly shows the OPDC’s bid to the Government’s Housing Infrastructure Fund contained a significant inaccuracy.

The development corporation claimed in its 2018 proposal that it had secured the support of local landowner Car Giant, and would begin by developing that site.

The used car dealer’s land would have made up around 20 per cent of the proposed regeneration site.

But communication between the OPDC and Car Giant had broken down the year before, and at the time of the bid the company had already made clear that it did not wish to sell.

Last month, Old Oak leaders admitted that they could not progress with their original plans, and dropped the threat of a compulsory purchase of Car Giant.

This forced the developer to give up the £250 million funding secured from Government – but the documents published this week show that its claim to the money was based on inaccuracy.

Susan Hall, chairman of the London Assembly’s budget performance committee, warned that the funding bid was “clearly built on sand”.

She said: “Projects commissioned by the Mayor and making use of public funds require full transparency and the OPDC is no exception to this.”

The bid revelations and lost funding are the latest blows to the scheme, which faces significant uncertainty over the future of HS2.

The project was planned around the interchange of the high speed rail link and Crossrail at Old Oak Common– and OPDC bosses have admitted that their development is “totally dependent” on the new station.

Last year, a planning inspector’s report said the scheme should reduce its targets to 14,200 homes and 37,590 jobs.

But Mr Khan continues to back the project and said the OPDC will now focusing on developing other parts of the planned site.

He said: “I am confident that OPDC’s new approach, including working with Network Rail and HS2 to bring forward substantial sites under their control, will mean that the foreseen scale of growth and new housing remains achievable.”

A spokesperson for OPDC said: “The business case named a large number of stakeholders as supporting the bid, and did not take into account that Car Giant was at this stage minded to abandon their earlier plans due to rising land values.

“During the negotiations, Government officials were made fully aware of the changing status of Car Giant’s plans.”