High Quality Content by WIKIPEDIA articles! The Social Democratic Party (SDP) was a political party in the United Kingdom that was created on 26 March 1981 and existed until 1988. It was founded by four senior Labour Party `moderates`, dubbed the `Gang of Four`: Roy Jenkins, David Owen, Bill Rodgers and Shirley Williams. At the time of the SDP`s creation, Owen and Rodgers were sitting Labour Members of Parliament (MPs); Jenkins had left Parliament in 1977 to serve as President of the European Commission, while Williams had lost her seat in the 1979 general election. The four left the Labour Party as a result of policy changes enacted at the January 1981 Wembley conference which committed the party to unilateral nuclear disarmament and withdrawal from the European Economic Community. They also believed that Labour had become too left-wing, and had been infiltrated at constituency level by Trotskyist factions whose views and behaviour they considered to be at odds with the Parliamentary Labour Party and Labour voters.