The Prime Minister is today expected to put High Speed 2 at the heart of the Government’s growth agenda and confirm the line will be extended to Leeds and Manchester.
It could spark anger in Oxfordshire and Buckinghamshire where the outcome of a legal challenge into the project is still to be made.
It's claimed the Government failed to properly consult on the scheme.
In a speech Mr Cameron will say HS2 is going ahead and will be the most important project in the UK to create jobs and boost the economy. He is attending a Cabinet meeting in the north where he is expected to make the comments.
Those opposed led by Buckinghamshire and Oxfordshire County Councils say the scheme will destroy large parts of The Chilterns.
It would link London and Birmingham and then go on to Leeds and Manchester. The cost is £32bn.
It would pass close to Wendover, Aylesbury, Bicester and north of Banbury.
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Dry with sunny spells to start. Warm with hazy sunshine this afternoon
A dry and bright start with long spells of sunshine into this afternoon and feeling fresher
Fine this evening, then dry overnight with mist likely in places. Sunny spells tomorrow morning with hazy sunshine in the afternoon