EXPERTS yesterday picked apart key figures used to justify the benefits of the High Speed 2 project, with one describing the modelling methods as “essentially made up”. MPs heard from several academics who doubt that the rail link will generate £15bn a year for the British economy, and Treasury select committee chair Andrew Tyrie said afterwards that the claim “has no firm statistical foundation”. Henry Overman, a professor at the London School of Economics who formerly advised the government on HS2, said KPMG, which provided the forecast, “applied this procedure which is essentially made up”. “I just don’t understand why the £15bn number was allowed to go out there,” he added. Dan Graham, a professor of statistical modelling at Imperial College, added that “undoubtedly the work could be done better”. KPMG defended its sums, with head of infrastructure Lewis Atter telling the panel of MPs that the sum is “a considered estimate”, which if anything is overly conservative. The criticism comes just a week after the government lowered the scale of the benefits it expects to see from the link between London and the north, to reflect the budget rise to £42.6bn earlier this year. It now predicts that HS2 will generate £2.30 for every £1 spent on the scheme, down from its previous forecast of £2.50.