Cameron was born in Happy Valley, South Australia, the son of Mary Ann and John Cameron. His parents were both immigrants from Scotland. He was educated at state schools and worked on his father's farm at Happy Valley until 1916, when he joined the First Australian Imperial Force and fought on the Western Front. He was gassed while in the front, suffering severe damage to his heart and lungs. After World War I Cameron took up farming near Loxton as part of a soldier settlement scheme, and became active in the newly formed Country Party.
Cameron did not have long to wait for ministerial preferment; in 1937 he was appointed an assistant minister in the government of Joseph Lyons. In November 1937, Cameron stood for the deputy leadership of the Country Party following the retirement of Thomas Paterson; he did not win enough votes to make the second ballot. He briefly served as acting minister for commerce in 1938, and during that time became the first minister to be "named" by the Speaker. Later that year, he became Postmaster-General. He temporarily suspended radio 2KY's licence because he objected to political views expressed on it.
Leader of the Country Party
Cameron was elected leader of the Country Party on 13 September 1939, following the resignation of Earle Page. He defeated John McEwen by seven votes to five, with two abstentions. According to McEwen, the result was skewed by the absence of four MPs who had refused to sit with the Country Party with Page as leader – a motion to re-admit them was defeated by seven votes to six. McEwen claimed in his memoirs that the dissident MPs were "all strong supporters of mine and, had they been allowed to vote, I would have won the election". They were all re-admitted to the party a few months later. In March 1940, Cameron took the Country Party back into the coalition government under Menzies, becoming the de facto deputy prime minister as well as Minister for Commerce and Minister for the Navy. After the 1940 election, however, the Country Party tired of Cameron's domineering style, and replaced him as leader with Arthur Fadden. Cameron then immediately resigned from the ministry, and from the Country Party: he joined Menzies's party, the United Australia Party. He rejoined the Army and spent the rest of the war on active service in the Directorate of Military Intelligence at Army Headquarters, Melbourne, where he did useful work on the Japanese order of battle. While he was in the service, he faced what would be his only really close electoral contest. At the 1943 election, trade unionist Harry Krantz slashed Cameron's majority from a comfortably safe 15.9 percent to an extremely marginal 1.7 percent. Cameron was left as the only non-Labor MP from South Australia, and the only non-Labor member outside the eastern states.
Cameron followed most of the UAP into Menzies's new party, the Liberal Party, and when the Liberals won the 1949 elections Menzies appointed him Speaker of the House: mainly, it was said, to keep him out of the Cabinet. He presided over the House with an autocratic style that caused a number of celebrated rows with members on both sides. Cameron's health never recovered from his World War I gassing, and in August 1955 he contracted influenza. Despite this, he fought that year's election and was handily reelected. He would die of a heart attack in August in Royal Prince Alfred Hospital, Sydney.
Personal life
Cameron married Margaret Eileen Walsh on 15 April 1925. They had a son and a daughter together; his daughter predeceased him. Cameron was raised Presbyterian, but later converted to Catholicism, which was his wife's religion. He was known for choosing to affirm the oath of office, citing Jesus's admonition to "swear not at all".