Vincent Cable began his political life with Labour, leaving when the party lurched leftwards in the early 1980s to join the SDP.

He had been an adviser to John Smith when the future Labour leader was trade secretary in the James Callaghan administration and co-authored a leaflet with a young Gordon Brown.

Mr Cable, former chief economist for oil giant Shell International, was elected MP for Twickenham in 1997 after running for every election since 1983. Before covering his current Treasury brief he was trade and industry spokesman.

He was a key supporter of Sir Menzies Campbell's successful party leadership campaign in 2006 and was rewarded with the position of deputy leader.

Following Sir Menzies' resignation, he becomes acting leader, but has ruled himself out of running for the job on a permanent basis.