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William McMahon

Sir William McMahon was an Australian politician and lawyer who served as the 20th prime minister of Australia from 1971 to 1972.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

Sir William McMahon was an Australian politician and lawyer who served as the 20th prime minister of Australia from 1971 to 1972. A senior Liberal Party figure, he held multiple ministerial offices over a long parliamentary career and later became a backbench critic after losing office.

Early life and education

William McMahon was born in Sydney in 1908 and later trained as a lawyer. Biographical sources note his legal background before he entered federal politics.

Political career

McMahon entered the Australian Parliament in 1949 and became a senior Liberal Party minister over the following decades. He served in key portfolios such as Treasury and Foreign Affairs before becoming party leader and prime minister in 1971.

Prime ministership

McMahon became prime minister in March 1971 after John Gorton lost party support. His government was defeated by Labor in the 1972 federal election after a term of about 21 months.

Later life and death

After leaving the prime ministership, McMahon stayed in parliament until 1982 and later worked in advisory roles. He died in Sydney in 1988 at age 80.

Key facts

  • McMahon was Australia’s 20th prime minister and served from March 1971 to December 1972.
  • He was a member of the Liberal Party and succeeded John Gorton as both party leader and prime minister.
  • Before becoming prime minister, he held several ministerial portfolios, including Treasury and Foreign Affairs.
  • He represented the federal seat of Lowe from 1949 until 1980.
  • After leaving office, he remained in parliament until 1982 and later worked outside politics before retiring.

Frequently asked questions

Who was William McMahon?
William McMahon was an Australian politician and lawyer who served as the 20th prime minister of Australia from 1971 to 1972.
Which party did William McMahon belong to?
He was a member of the Liberal Party of Australia.
When was William McMahon prime minister?
He served as prime minister from 10 March 1971 to 5 December 1972.
What other offices did he hold?
He held several ministerial roles, including Treasurer and Minister for Foreign Affairs.
When did William McMahon die?
He died on 31 March 1988 in Sydney at the age of 80.
What electorate did he represent?
He represented the federal seat of Lowe in New South Wales from 1949 to 1980.

References

  1. Encyclopaedia Britannica — https://www.britannica.com/biography/William-McMahon
    Supports: Birth and death details, political affiliation, offices held, and prime ministership dates.
  2. National Museum of Australia — https://www.nma.gov.au/explore/features/prime-ministers/billy-mcmahon
    Supports: Prime ministerial term, political context, withdrawal of troops from Vietnam, and death details.
  3. National Archives of Australia — https://www.naa.gov.au/explore-collection/australias-prime-ministers/william-mcmahon/after-office
    Supports: Post-office career, retirement from parliament, later work, knighthood, and death.
  4. Museum of Australian Democracy — https://www.moadoph.gov.au/explore/democracy/election-speeches/william-mcmahon-1972
    Supports: Dates of birth and death, prime ministerial term, party leadership, and representation of Lowe.
  5. Woollahra Municipal Council — https://www.woollahra.nsw.gov.au/Library/Woollahra-Plaque-Scheme/Sir-William-McMahon
    Supports: Political career overview, prime ministerial term, and leadership transition from John Gorton.