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
Department of the Prime Minister and Cabinet (Australia) The Group was formerly led by the post of National Security Adviser (NSA) which was established in December 2008 by Prime Minister Kevin Rudd and disbanded in 2013 by Prime Minister Tony Abbott with responsibilities transferred back to the Deputy Secretary of the National Security and International Policy Group. The inaugural NSA was Major General Duncan Lewis serving until 2011. The second and final NSA was Dr Margot McCarthy serving from 2011 to 2013. The Special Adviser to the Prime Minister on Cyber Security and their office is responsible for national leadership on cyber security policy, coordination of priorities for