25-01-1981 Roy Jenkins, David Owen, Bill Rogers and Shirley Williams, SDP Launch, Limehouse, London 1981. The Gang of Four leaving the Labour Party and forming a Council for Social Democracy, as they said the pa... © John Sturrock

26-03-1981 The Gang of Four split from the Labour Party to form the SDP 1981 (L to R) Roy Jenkins, David Owen, Bill Rodgers and Shirley Williams © Peter Arkell

09-10-1981 Shirley Williams speaking SDP conference London 1981 © Martin Mayer

09-10-1981 Shirley Williams speaking SDP conference London 1981 © Martin Mayer

09-10-1981 Bill Rodgers speaking, SDP conference London 1981 © Martin Mayer

09-10-1981 Bill Rodgers speaking, SDP conference London 1981 © Martin Mayer

14-02-1982 Sue Slipman speaking, SDP conference 1982. She left the Communist Party to join the SDP as a founder member © Martin Mayer

14-02-1982 Sue Slipman speaking, SDP conference 1982. She left the Communist Party to join the SDP as a founder member © Martin Mayer

02-07-1982 Roy Jenkins elected leader of the Social Democratic Party 1982 © NLA

02-07-1982 Roy Jenkins elected leader of the Social Democratic Party 1982 © NLA

02-07-1982 Roy Jenkins elected leader of the Social Democratic Party 1982 © NLA

22-04-1983 General Election Campaign 1983. Woman glances up at a billboard poster advertising an SDP Party Political Broadcast. Depicting Margaret Thatcher as The Tin Man and Michael Foot as The Scarecrow, chara... © Stefano Cagnoni

02-05-1987 Conservative Party 1983 general election poster: What are the SDP's Policies? Ten bottles of claret can be won for the best guess, London. The opposition vote was split almost evenly between the SDP/L... © John Harris

04-03-1985 London 1985 George Melly, Ted Knight of Lambeth and local council leaders protest against Rate capping, head of Roy Jenkins on a plate © NLA