Benn is the third generation of a family tradition

The appointment of Hilary Benn as Secretary of International Development makes him the third generation of his family to serve in the Cabinet and the fourth in a line of MPs with political roots in the 19th century Liberal party.

Mr Benn's great grandfather was John Benn, Liberal MP for Wapping from 1892 to 1895. Like Tony Benn and Hilary Benn he also successfully fought a by-election, in 1904, in Devonport.

His son, William Wedgewood Benn, followed his father into the Liberal party, taking his old seat in Tower Hamlets at the 1906 general election. At 28 he was the youngest MP and in four years joined the government as a Whip.

After resigning as an MP to fight in the First World War, where he served at Gallipoli and as a decorated member of the Royal Navy Air Service, he was elected again as a Liberal MP in 1918. But in 1926, following the appointment of Lloyd George, he joined the Labour party.

He resigned his seat but returned to parliament in 1927. After the Labour victory in 1929 Ramsay MacDonald appointed him Secretary of State for India. In 1940 he was asked to become a Labour peer assuming the hereditary title of Viscount Stansgate. He served in Attlee's cabinet as Secretary of State for Air until 1946.

His son Tony Benn, born Anthony Neil Wedgwood Benn, was elected an MP at 25. But his father's title - which he inherited after the death of his elder brother in the war - almost cost him his place in the House of Commons. The Second Viscount Stansgate disclaimed his title for life after by-election victory in 1961, following a long battle which earned him an international reputation.

Tony Benn joined the Wilson governments of the 1960s, where he served as postmaster general and then the first minister in the new technology ministry.

He joined the Wilson cabinet of 1974 as Secretary of State for Industry and was moved to Secretary of State for Energy, a post he held under Wilson and Callaghan. But it was after the defeat of Labour in 1979 that Tony Benn began to champion the hard left. His role as scourge of the mainstream Labour party earned him the tag, "Bennite" and he used his skills in oratory to attack the right of the party and those who favoured cooperation with Liberals.

After retiring from Parliament in 2001, and seeing his son take up his seat in the House of Commons, he has continued to attack the Government over Iraq and privatisation.