Tas Bull was born in Sydney in 1932. His first name was a combination of Tasmania and Norway, the respective birth places of his mother and father. He grew up in a working-class household in Tasmania. His father, an electrical contractor, had been a seaman. He was raised a member of the Salvation Army. He went to sea in 1946 and became active in the Seamen's Union of Australia (SUA), then aligned with the Communist Party of Australia (CPA), which Bull joined in 1951. He left the CPA in 1959, following the suppression of the Hungarian revolution by the Soviet Union.