Lord Ashcroft, the former Conservative treasurer and a billionaire businessman, was appointed to a senior Tory role yesterday by the party's leader, David Cameron.

Lord Ashcroft was appointed a deputy chairman of the party and remains a member of its ruling board.

Lord Ashcroft
Lord Ashcroft is the party's biggest donor

He will be responsible for Conservative Future, the party's youth wing, target seats and opinion research.

Before the last general election, Lord Ashcroft pledged a £2 million fighting fund for marginal constituencies. After the party's third consecutive defeat in May, he commissioned a devastating report into what went wrong.

Lord Ashcroft is the party's biggest donor, having contributed about £10 million.

As treasurer under William Hague's leadership, he kept the party afloat with a series of seven-figure gifts. He was controversially awarded a peerage in 2000 on Mr Hague's recommendation after being rejected for a title twice by Tony Blair.

Lord Ashcroft, who has business interests in Belize, had to give an assurance that he would take up permanent residence in Britain.