Sir David Higgins, the mastermind behind the High Speed 2 railway, believes that an equivalent track in France would come in at one-third of the cost.

The HS2 Ltd chairman led a delegation to south-west France in the summer to look into why the 302km Tours-Bordeaux high-speed line, and 38km of connecting lines to the existing rail network, cost little more than £6bn.

A source close to HS2 said that even after “stripping out” differences in topography and expensive new stations, such as a hub in Crewe, “the comparisons with France were not good, kilometre for kilometre”.

It is understood that Sir David will give little detail on costs in his report on the second phase of HS2, a Y-shaped route linking Birmingham to Manchester and Leeds, because of that visit. He has challenged his team to find ways of reducing costs in Phase Two, and he recently ordered that the overall budget be reviewed every six months.

The £21.4bn-budget first phase, between London and Birmingham, reduces the journey time to 49 minutes. It is due for completion by 2026.

Tomorrow, George Osborne, the Chancellor, will announce plans for what has been dubbed HS3, a line across the Pennines that would act as a major economic boost to the North. Writing on page 42 today, the Shadow Chancellor, Ed Balls, and former Transport secretary Lord Adonis dismiss the promise as “pre-election posturing”.