Born in Port Elizabeth, he was radicalised after working for the South African Bantu Affairs Administration and moved to Britain.
He was a lecturer at the universities of Leeds (1949–62) (where he was a leading left-wing activist), Birmingham (1962–64), Durham (1964–70), Warwick (1970–79 and 1984–90), Aston (1979–84), Toronto (1974–75), Cape Town (1991) and New York (1996).
His academic work involved the analysis of conflict as a key problem of both society and sociological theory.
Rex worked "at the universities of Leeds (1949-62); Birmingham (1962-64); Durham (1964-70); Warwick (1970-79 and 1984-90); Aston (1979-84); Toronto (1974-75); Cape Town (1991); and New York (1996).
Theory and practice was for him always a dynamic issue and led to his demands for "objective" research and comment while being a political radical involved in the UK's Campaign for Nuclear Disarmament (CND) and the New Left Review.