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
Deputy prime minister Deputy prime minister A deputy prime minister or vice prime minister is, in some countries, a government minister who can take the position of acting prime minister when the prime minister is temporarily absent. The position is often likened to that of a vice president, but is significantly different even though both positions are "number two" offices. The position of deputy prime minister should not be confused with the Canadian Deputy Minister of the Prime Minister of Canada, a nonpolitical civil servant position. Also, the Deputy Prime Minister of Canada does not act as a "number two". The states of