1956, but declined to seek the nomination, citing personal reasons. He instead suggested his friend Norman Kirk stand in for Lyttelton, and became electorate organiser when Kirk took the seat. He later stood as a Labour Party candidate for the Christchurch City Council at a 1958 by-election, but was unsuccessful. At the he was selected as the Labour candidate in the electorate, but later withdrew his candidature. When Kirk switched to the electorate in 1969, McGuigan stood to replace him for Lyttelton and won selection. McGuigan was elected to Parliament in the in the electorate. When Labour formed a government after the , Norman Kirk appointed McGuigan as Minister of Railways, and Minister of Electricity. As Minister of Electricity he was instructed by Kirk in February 1973 to not raise the level of Lake Manapouri fulfilling Labour's election pledge during the Save Manapouri campaign. He created an independent body, the Guardians of Lake Manapouri, Monowai, and Te Anau (composed of leading members of the protest) to oversee management of the lake levels. He also had to react to New Zealand's growing power demands, but refused to resort to nuclear power, reaffirming the government's anti-nuclear stance. He became known as one of the economic realists in the cabinet and frequently argued against tear-away spending. After Kirk's sudden death, the new prime minister, Bill Rowling, appointed McGuigan to the portfolio that he had really wanted - Minister of Health. He oversaw completion of the White Paper on Health, which called for establishment of partly elected district health boards. The plan was thrown out however by the incoming National Government. He also approved a cardio-thoracic unit at Christchurch Hospital, but it took twenty years until such a unit was established. McGuigan visited Vietnam near the end of the Vietnam War. New Zealand was providing aid to help rebuild Vietnam's health infrastructure following withdrawal of New Zealand troops. Inspecting the work, he was stunned by evidence all around of the effects of war damage and that gunfire could still be heard clearly in the distance. McGuigan was unexpectedly defeated in the by Colleen Dewe of the National Party. At the 1980 local-body elections he was elected a member of the North Canterbury Hospital Board. Despite being a first time candidate he "topped the poll" receiving more votes than any other candidate at the election. McGuigan was re-elected to the board in 1983, but did