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
Office of the Prime Minister and Privy Council Office of the Prime Minister and Privy Council The Office of the Prime Minister and Privy Council () building, formerly known as the Langevin Block (, ), is an office building facing Parliament Hill in Ottawa, Ontario, Canada. As the home of the Privy Council Office and Office of the Prime Minister, it is the working headquarters of the executive branch of the Canadian government. The term Langevin Block was previously used as a metonym for the Prime Minister's Office and the Privy Council Office. The building was named after Father of Confederation and cabinet minister Hector Langevin. On June