The by-election was caused by the death of the sitting Labour MP Guy Barnett. Labour had held the constituency since 1945, although their majorities had been declining and at the previous general election in 1983 Barnett had only been 1,211 votes ahead of the Conservatives. Rosie Barnes, the SDP candidate, had strong links with the local area and her husband was a local councillor who was also her election agent. The Alliance targeted the Tory vote which collapsed and Barnes was elected with a majority of 6,611. She held the seat at the general election four months later but lost it to Labour in 1992.