The NAO warned of a £3.3bn funding gap in the £33bn scheme, and said the government has made poor arguments to support the claim that faster rail travel to the north of the country will help rebalance the economy.
It also pointed out past errors and outdated information in the benefit-cost calculations on the scheme and concluded that the timetable is “overambitious”.
“It’s too early in the High Speed 2 programme to conclude on the likelihood of its achieving value for money,” said NAO head Amyas Morse. “Our concern at this point is the lack of clarity around the [Department for Transport’s] objectives. The strategic case for the network should be better developed at this stage.”
Transport secretary Patrick McLoughlin brushed off much of the criticism. “I do not accept the NAO’s core conclusion,” he said in a statement. “We are not building HS2 simply because the computer says ‘yes’. We are building it because it is the right thing to do to make Britain a stronger and more prosperous place.”