Mr Osborne plans to quit at the end of this month to concentrate on campaigning in Tatton for the General Election, which is expected in May.

"He (William Hague) has known all along that my ambition was to become a member of Parliament," Mr Osborne said yesterday (Tuesday).

"On the one hand he is delighted that I will be fighting a seat, but on the other he will be sorry to see me go, I hope."

His successor is Dan Hannan, a Eurosceptic widely believed to have been behind Mr Hague's weekend speech when he warned that a second-term Labour Government would turn Britain into a 'foreign land'.

Mr Osborne, who faces a tough battle in Tatton against at least five candidates, has been Mr Hague's speechwriter for four years.