Stephen Barclay went beyond the normal formulation in saying the project was part of the Conservatives promise to voters in last month’s election

A cabinet minister has said HS2 is a “key part” of the Tories’ promise to northern voters fuelling speculation that Boris Johnson is set to approve the controversial project.

Stephen Barclay, the Brexit secretary, said his “gut feeling” was that the rail link will receive the go-ahead within the next few weeks despite heavy opposition among some of Mr Johnson’s aides and MPs.

A review of the high-speed rail line, initially between London and Birmingham but later extending to Manchester and Leeds, found that costs could rise to £106 billion, approaching twice the initial sum.

The official spending watchdog, the National Audit Office, criticised the Department for Transport for failing to account for the range of uncertainties and said it had not properly protected