He grew up in Stepney in the East End of London, and studied chemistry at Chelsea Polytechnic before joining the Communist Party of Great Britain (CPGB).
He was an active anti-fascist in the 1930s, protecting communist meetings from attacks and heckling the leader of the British Union of Fascists, Oswald Mosley.
[1] In the late 1930s, Wainwright was the national organiser for the Young Communist League and editor of Challenge, its newspaper.
He contributed to the Morning Star as science editor, and served as Assistant General Secretary of the party from 1956 until 1959.
In 1985, he was dropped as science editor from the Morning Star amid factional struggles, but was reinstated after protests.