Their report published today calls for “fundamental reset” of the project by the summer.

They warn that they remain sceptical about the Government’s ability to successfully deliver its revised programme following a litany of failures and unheeded warnings.

The report says that the HS2 programme has become a casebook example of how not to run a major project.

“It is unacceptable that over a decade into the programme we still do not know what it will cost, what the final scope will be, when it will finally be completed or what benefits it will deliver,” states their report.

Watchdog MPs also highlighted the significant challenges facing plans to build the Euston Station terminus using a third party development body.

As plans stand, HS2 will open with a terminus at Old Old Common. Despite plans to launch the TBM tunnel drive next year to Euston from Old Oak Common there are no detailed plans or timescale for delivering the Euston Terminus, warns the report.

The Government’s Euston plans currently rest on the £6bn cost being significantly underpinned by the private sector.

The PAC said it was concerned that there is no clear plan for this, and said it was sceptical the private sector would come forward to the level required.

The government confirmed that HS2 would terminate at London Euston in the Autumn 2024 budget.

However, the PAC warns the Department still does not yet have a plan for the work at Euston which includes: the HS2 station, the existing Network Rail station, the underground station, and the commercial and housing developments near the station.

“In addition, the Department intends the work to be sustantively privately funded, but it is unclear how achievable this goal is,” they warn.

Sir Geoffrey Clifton-Brown MP, Chair of the Committee, said: “Our Committee has not made recommendations in our report on delivering better outcomes for HS2’s future passengers.

“We are long past that point. It is time to deal with HS2 as what it is – a cautionary tale that should be studied by future Governments in how not to run a major project.

“We are sceptical of Government’s ability to successfully deliver even a curtailed scheme, one which we already know will on its face bring very poor value for money. The question has instead become: what possible benefit can the Government now salvage for the taxpayer, from a mess that presents real risks to the UK’s overall reputation?”

The Department for Transport’s present cost estimated set out in November 2023 is £45bn to £54bn compared with HS2 Ltd’s latest estimate of £54bn to £66bn in June 2024.

Both cost estimates are still in 2019 prices, once adjusted for inflation, the total programme costs might be close to £80bn, states the report.