In June of 1971, the Liberal prime minister, William McMahon, celebrated 100 days in office.
McMahon’s tenure followed a period of instability and infighting in the government, which resulted in a challenge by Defence Minister Malcolm Fraser to then prime minister John Gorton. A tied vote in the party-room led to Gorton relinquishing the leader’s position and the election of McMahon, who became prime minister on March 10, 1971.
McMahon entered parliament in 1949. He had served as a minister continuously since July 17, 1951, when Robert Menzies appointed him Minister for the Navy and Minister for the Air Force. He went on to serve in a number of portfolios, culminating in Treasury and Foreign Affairs. To this day, he holds the record for the longest continuous service as a minister and prime minister: 21 years, 4 months, 18 days.