In the late 1930s, Wainwright was the national organiser for the Young Communist League and editor of Challenge, its newspaper. He joined the Home Guard during World War II while producing publicity for the CPGB, then after the war led the British-Soviet Friendship Society. He contributed to the Morning Star as science editor, and served as Assistant General Secretary of the party from 1956 until 1959.[1]
Wainwright retired from the CPGB's executive committee in 1975. In 1985, he was dropped as science editor from the Morning Star amid factional struggles, but was reinstated after protests.[2] He remained a member of the CPGB until its dissolution, which he opposed, and joined its successor, Democratic Left.[1]