1981 Crosby by-election

Shirley Williams became the first MP elected under the SDP label on November 26, 1981, overturning a Conservative majority of 19,272 in a safe seat on Merseyside. She took almost half the vote, and both the Conservatives and Labour fell by more than 15 points. Her verdict that night, that there was no safe seat left in the country, captured the brief moment when the new party looked capable of breaking the two-party system altogether.