In the UK there is no formal office of deputy prime minister - the post is created entirely at the discretion of the serving prime minister.
The deputy prime minister possesses no particular power above their cabinet colleagues but the title may imply additional practical status, although the deputy PM does not assume the power of the prime minister in their absence or illness.
The first deputy prime minister was Clement Attlee, appointed by Winston Churchill during the Second World War.
Margaret Thatcher's right hand man, friend and confidant William Whitelaw (Lord Whitelaw), served as deputy prime minister from 1979 to 1988.
From July 1989 until his resignation on 1 November 1990, Sir Geoffrey Howe (Lord Howe) was deputy prime minister.
John Prescott was Tony Blair's deputy prime minister and deputy party leader from the general election in May 1997 to Blair's resignation in June 2007.
Although Mr Prescott was replaced by Harriet Harman as deputy leader of the Labour party, Prime Minister Gordon Brown chose not to appoint a deputy prime minister.
The responsibilities and styles of the incumbents in this post have varied greatly over the years.