John Gilbert Evans was born in Ystalyfera in the Swansea Valley. Educated at the University of Wales in Aberystwyth and Swansea, prior to retirement he was head of educational studies at the University of Wales, Newport. He was a member of the study group set up by the Welsh Council of Labour in 1969 to prepare evidence to the Royal Commission on the Constitution, 1969-1973. At the 1970 general election, he was the Labour Party candidate in Flint West.