Sir Vince Cable will be crowned leader of the Liberal Democrats on Thursday with a pledge to become Britain's second biggest party.

The former Cabinet minister will be unveiled as the party's leader at a Westminster hotel at teatime on Thursday and will say he wants the LibDems to become bigger than the Tories.

The LibDems had 101,000 members at the end of May - behind the Tories which last year said they had 134,000 members, down from 253,600 in 2005.

A spokesman for Sir Vince said the party's membership was "at its highest since its formation" with the merger between the Liberals and the Social Democrats in 1988.

He added: "Vince has huge ambitions. Since the general election there has been serious growth in party membership.

"Having more members than the Conservative party is a realistic target which Vince hopes to achieve soon."

Sir Vince will replace Tim Farron, who quit as party leader days after the election campaign in which he had faced repeated questioning over his religious beliefs.

The Telegraph disclosed last week how Sir Vince is considering a plan to pay students to go to university.

One of Sir Vince's idea is the possibility of following the Welsh government’s lead by giving all university students in England at least £1,000 a year to study.