The seat had become vacant on 8 May 1985, when the constituency's Conservative Member of Parliament (MP), Tom Ellis Hooson, had died at the age of 52.

Tom Hooson had been Brecon and Radnor's MP since the 1979 general election, when he gained the seat from the Labour Party.

Andre Charles Leopold Genillard was an Independent who campaigned as a Free the World from Multiple Sclerosis candidate.

Livsey held the seat for the Liberals at the 1987 general election, with a majority of just 56 over the Conservative Jonathan Evans with Labour dropping to third place.

[2] This meant that Brecon and Radnor was the only seat that the Conservatives lost at a by-election in the 1983-1987 parliament that they failed to regain at the 1987 election.