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 Portugal elections, after having heard the parties represented in the Parliament. Usually, the person named is the leader of the largest party in the previous election, but there have been exceptions over the years. Since the Middle Ages, some officers of the Portuguese Crown gained precedence over the others, serving as a kind of prime ministers. Over time, the role of principal officer of the Crown fell upon the "chanceler-mor" (chancellor), the "mordomo-mor" (mayor of the palace) and the "escrivão da puridade" (king's private secretary). The first modern prime minister of Portugal was Pedro de Sousa Holstein, Marquess of Palmela, who