The SDP–Liberal Alliance was a formal electoral partnership in the United Kingdom between the Social Democratic Party and the Liberal Party during the 1980s. The arrangement aimed to present a centrist alternative to the Conservative and Labour parties and jointly contested the 1983 and 1987 general elections. The alliance secured substantial shares of the national vote—about 25% in 1983 and roughly 23% in 1987—but won relatively few seats under the first-past-the-post system. In 1988 the two parties united to create a single party that became known as the Liberal Democrats.
Origins
The pact grew out of the formation of the Social Democratic Party in the early 1980s and a desire by both groups to coordinate candidates and policy to avoid splitting the centre-left vote. The Liberal Party, with a long history as a third party in British politics, agreed to cooperate with the newer party rather than compete directly in many constituencies. Together they presented joint election programmes and shared campaigning resources.
Electoral history and outcome
As an alliance, the two parties achieved notable levels of popular support in national voting, and they enjoyed a number of strong results in by-elections and at local level. However, the British electoral system translated their national vote into relatively few parliamentary seats. Debates over long-term unity and the best way forward continued through the decade, and in 1988 the partners decided to merge into a single organisation, consolidating most of their members and structures into what is now the Liberal Democrats.
- Active period: early 1980s until 1988
- Main purpose: joint electoral strategy for general elections
- Result: merger in 1988 forming a new party
For more detail on the component parties, see the entries on the Liberal Party.