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
Minister of Foreign Affairs (New Zealand) the field. Several New Zealand Prime Ministers including Peter Fraser, Walter Nash, Keith Holyoake, and David Lange held the External Affairs portfolio. The most recent Prime Minister to do this is Helen Clark in 2008 as Acting Minister, and prior to her was Mike Moore, in 1990. Thirteen Prime Ministers have served as Foreign Minister for all or part of their terms. New Zealand has had 27 foreign ministers (regardless of exact title). The longest-serving was Keith Holyoake, who held the post for the duration of his 11-year premiership. The second longest-serving, and the longest-serving who was not also Prime