Cameron was the most powerful figure in the South Australian labour movement in the years immediately after World War II. At the 1949 election, he was elected to the House of Representatives for the safe Labor seat of Hindmarsh and left his brother Don (later a senator) in charge of the South Australian AWU. He rapidly made his mark as one of the most aggressive and uncompromising Labor members ever to enter the Australian Parliament. Cameron regarded the conservatives with a deep and personal hatred and made no secret of it. He rapidly emerged as one of the leaders of the left wing of the Caucus, led at that time by Eddie Ward, who became Cameron's mentor. Nonetheless, he was an intelligent and able parliamentarian.