The constituency's Labour Member of Parliament (MP), Ioan Lyonel Evans (10 July 1927 – 10 February 1984), had died at the age of 56.

He served on the West Bromwich education committee and acted as Labour Party agent for the general elections in 1955 and 1959 in Birmingham Small Heath.

She had been a Member of the European Parliament (MEP) for Mid and West Wales 1979–1984 and had contested the Westminster seat of Denbigh in 1970.

Felix Franc Elfed Aubel, a postgraduate research student born in 1960 was the candidate of the Social Democratic Party (SDP) and represented the SDP-Liberal Alliance.

James Norwich Arbuthnot, a barrister born in 1952, represented the Conservative Party.

She was a senior social services officer with Mid-Glamorgan County Council and was aged 36 at the time of the by-election.