Politician. Born in Glasgow, the son of a butcher, Mabon was educated at North Kelvinside Academy. He served in the Lanarkshire coal mines as a Bevan Boy during World War II. Thereafter he studied medicine at the University of Glasgow and was involved in student politics. He was elected Member of Parliament for Greenock in 1955, representing the Labour and Co-operative Party alliance, holding this seat until in 1983. Mabon left Labour for the new Social Democratic Party (SDP) in 1981 but failed to regain his parliamentary seat in 1983. He did not like the merger of the SDP with the Liberals and rejoined the Labour Party in 1991.
Mabon served as Under-Secretary of State for Scotland (1964-67) and then Minister of State for Scotland (1967-70) in Harold Wilson's administration, and then Minister of State in the Department of Energy (1976-79) under James Callaghan. During the 1970s he spent his time defending social democratic values within the Labour Party, against the rise of the left-wing.
He died at his home in Eastbourne in the South of England.
