A popular figure with the Lib Dem grassroots, Simon Hughes has twice stood for the party leadership.

In 1999 he was beaten by Charles Kennedy. His 2006 campaign was overshadowed by his admission to a tabloid newspaper that he had had gay relationships.

The North Southwark and Bermondsey MP also stood unsuccessfully against Ken Livingstone for London mayor in May 2004, coming third.

A barrister by profession, he is known for his views on civil liberties and has served as the party's justice spokesman. He is also an anti-nuclear campaigner, although his public backing for Sir Menzies Campbell's "wait and see" policy on replacing Trident helped the party leader win a crucial conference vote in 2007.

His loyalty was rewarded in Sir Menzies' July reshuffle with a post shadowing the commons leader.