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
Prime minister supply, most constitutional systems require either: The latter in effect allows the government to appeal the opposition of parliament to the electorate. However, in many jurisdictions a head of state "may" refuse a parliamentary dissolution, requiring the resignation of the prime minister and his or her government. In most modern parliamentary systems, the prime minister is the person who decides when to request a parliamentary dissolution. Older constitutions often vest this power in the cabinet. In the United Kingdom, for example, the tradition whereby it is the prime minister who requests a dissolution of parliament dates back to 1918. Prior