Social Democratic Party (UK)

The party of the 1981 Gang of Four defectors from Labour, merged into the Liberal Democrats in 1988.

Overview

The SDP launched in 1981 when Roy Jenkins, Shirley Williams, David Owen, and Bill Rodgers left Labour, judging it captured by the hard left. The Alliance with the Liberals polled over 25 percent in late 1981 and won spectacular by-elections, but the 1983 general election returned only 23 seats under first past the post despite six million votes. The two parties merged in 1988 into the Liberal Democrats, though Owen led a rump SDP to dissolution by 1990. The experiment showed both the ceiling of center breakaways in plurality elections and the appetite for a moderate social democratic alternative, a lesson repeated in later decades.