Background
McMahon was born in Hobart, Tasmania and was the son of a clerk who later became the Mayor of Balmain.
McMahon was born in Hobart, Tasmania and was the son of a clerk who later became the Mayor of Balmain.
He was educated at the Christian Brother"s school, Rozelle and was employed as a store manager for Coles & Company He served in the Second Australian Imperial Force in the Engineers" Corps for 5 years and reached the rank of Sergeant. He was elected as an alderman on Balmain Municipal Council between 1942 and 1944.
McMahon entered the New South Wales Parliament at the 1950 state election as the labor member for Balmain.
He defeated the sitting Labor member Mary Quirk who had lost her party endorsement. He retained the seat at 5 subsequent elections and retired at the 1968 election.
He was appointed as a Minister without portfolio in 1957 and became the first Minister for Lands in 1959. In 1960 he was commissioned as the Minister for Transport and he held this position until the defeat of the Labor government at the 1965 election.
At that election the Labor Party was criticized by the opposition for its lack of vision in providing transport infrastructure.
He was a member of the Australian Labor Party (ALP) and held ministerial positions including Minister for Transport and Minister for Lands. He later ran a delicatessen in Rozelle and was a member of the shop assistants" union. MacMahon was a member of the governments of Joseph Cahill, Robert Heffron and Jack Renshaw.