Adonis also revealed, in an interview with the Financial Times, that electrification of Brunel's Great Western Railway and the Midland main line, at a cost of £1.5bn, is also planned.
Adonis argued that the argument for a new line rests in a current chronic lack of capacity. The proposed high speed train line between London and Manchester would bypass the west coast main line, which is forecast to be at saturation point within 15 years in spite of its recent upgrade.
The Conservatives are already backing high speed, which increases the chances that the high speed link may actually be built. Adonis said a project with a 15-year construction time will need "the broadest possible political consensus" to succeed.