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 of New Zealand the family). Two prime ministers who died in office were buried in mausoleums: William Massey (died 1925) in the Massey Memorial in Wellington, and Michael Joseph Savage (died 1940) in the Savage Memorial at Bastion Point in Auckland. Assuming that Henry Sewell is counted as the first prime minister, 40 individuals have held the office since it was established. Some of these people have held it on several different occasions, with the record for maximum number of times being shared between William Fox and Harry Atkinson (both of whom served four times). The longest that anyone has served in the