Conservative leadership favourite Boris Johnson has ordered a review of whether HS2 is giving value for money as he studies “whether and how we proceed” with the project.

Johnson, who is the front-runner to succeed Theresa May as prime minister, has appointed former Crossrail and HS2 chairman Douglas Oakervee to lead the review of the £56B rail link from London to Birmingham and the north.

Both Johnson and Liz Truss, currently Chief Secretary to the Treasury but a potential Chancellor of the Exchequer in a Johnson Cabinet, have aired doubts about HS2.

The appointment of a former Crossrail boss is telling, according to an analysis in the Financial Times. It means that HS2 might become and east-west rather than north-south project.

Johnson’s team hope to be able to do for commuting in Greater Manchester and the West Midlands what he aimed to achieve as mayor of London. Crossrail is an east-west London rail link, improving commuter capacity.

The HS2 scheme could be scrapped if suitable alternatives can be found, such as the potential for a high-speed rail link connecting northern cities.

The HS2 project would be “reprofiled” to meet these changed objectives.

Work is already underway that could support this kind of rethink: earlier this month the government announced that design work on the northern phases of HS2 would allow an improved interface with commuter services overseen by Midlands Connect, the regional transport body.

The review comes soon after a House of Lords committee recommended a pause to reconsider the economic case for HS2.

The line north of Birmingham has already been delayed and political doubts about the project have been conspicuous for some time.

Johnson was speaking at a private leadership hustings for Conservative MPs.

"As Prime Minister of a great economy I’d have to think very, very carefully about instantly cancelling a huge national infrastructure project," Johnson said, according to a report by the Birmingham Post. "I’d have to look very carefully at the business case."

The Conservative leadership election moves to its third round of voting on Thursday 20 June.