Work on the London to Birmingham and Birmingham to Crewe sections of the line can now begin

Boris Johnson will call this week for work on the northern phase of HS2 to be speeded up as he gives the controversial project a green light.

The prime minister is expected to announce as early as tomorrow that the north-south line is getting the go-ahead. He is due to say that work on the London to Birmingham section and the spur from Birmingham to Crewe, forming the western arm of the Y-shaped route, can start immediately.

The second phase from Manchester to Leeds will be delayed for a short review to make sure that it is cost-effective. This may lead to changes to the proposed route and stations.

A Whitehall source insisted that there was a desire to “get spades in the ground” in