1982 Glasgow Hillhead by-election

Roy Jenkins won Glasgow Hillhead for the SDP on March 25, 1982, taking a Conservative seat with 33.4% of the vote and a majority of 2,038 after the death of Tam Galbraith. The win put the SDP's best-known founder back in the Commons, and he narrowly won the party's leadership that July. It is the clearest example of a by-election used as a launch pad for a leader, a playbook that returned 44 years later in Makerfield.