Prime Minister of Australia prime minister, otherwise William McMahon63. Robert Menzies was the oldest person to ever be prime minister, leaving office at 71 years old. The longest-serving Prime Minister was Sir Robert Menzies, who served in office twice: from 26 April 1939 to 28 August 1941, and again from 19 December 1949 to 26 January 1966. In total Robert Menzies spent 18 years, 5 months and 12 days in office. He served under the United Australia Party and the Liberal Party respectively. The shortest-serving Prime Minister was Frank Forde, who was appointed to the position on 6 July 1945 after the death of
Cabinet Secretary (Australian minister) Cabinet Secretary (Australian minister) The Cabinet Secretary was a former title conferred on an Australian minister responsible for assisting the Prime Minister to manage the day-to-day procedural and operational matters of the Cabinet and any Cabinet committees. As per all other ministers in the Westminster system, the Cabinet Secretary was a sitting member of Parliament, chosen by the Prime Minister and officially appointed by the Governor-General. The Cabinet Secretary was a portfolio minister of the Department of the Prime Minister and Cabinet and existed at various stages between 2007 and 2017, when the position was abolished. The Cabinet Secretary should