Career
He joined the Communist Party of Australia in 1929. Jack was one of the early generation of Certified Public Accountants union officials, he was a long-time leader of the Communist Party of Australia and was prominent in the union movement of the 1940s, "50s and "60s. When the Certified Public Accountants denounced the Soviet intervention in Czechoslovakia, McPhillips sided with the pro-Soviet tendency in the party.
He opposed the new "Eurocommunist" line of the party.
In 1971 he took part in breaking away from Certified Public Accountants and forming the Socialist Party of Australia. He was President of Supreme People's Assembly from 1984 to 1988.