Social Democratic Party (UK, 1988–1990)

The Social Democratic Party (SDP) was a short-lived political party in the United Kingdom, existing from 1988 to 1990. It was formed from the faction of the original Social Democratic Party (SDP) that voted to merge with the Liberal Party in 1988. The original SDP had been founded in 1981 by the "Gang of Four" – prominent former Labour Party politicians Roy Jenkins, David Owen, Shirley Williams, and Bill Rodgers – who felt the Labour Party had moved too far to the left.

After a period of electoral pacts known as the SDP–Liberal Alliance, a vote was held amongst members of both parties regarding a full merger. David Owen, leader of the SDP at the time, opposed the merger, advocating for the SDP to remain an independent force. However, a majority of SDP members voted in favour, leading to the formal merger with the Liberals to form the Social and Liberal Democrats (later the Liberal Democrats).

Owen and a minority faction, rejecting the merger, relaunched a smaller, independent SDP. This "continuing" SDP, led by Owen, struggled to gain traction. It achieved negligible electoral success in subsequent elections and struggled financially. The party was criticised for its small size and perceived irrelevance in the evolving political landscape.

The SDP, under Owen, officially dissolved in June 1990. A splinter group, the Social Democratic Alliance, continued under the SDP name for a few more years but also failed to gain significant political support. The remnants of social democracy in the UK were subsequently absorbed by other political parties, most notably the Labour Party and the Liberal Democrats. The 1988-1990 SDP is distinct from other parties with similar names throughout British history.