 He then became the Member of Parliament for Selwyn 1966–1972, then Rakaia 1972–1978, then Selwyn again 1978–1981.He was the Minister of Railways, Minister of Transport and Minister of Civil Aviation and Meteorological Services in the Third National Government from 1975 to 1981, and a close friend of Prime Minister Muldoon.They owned race horses together, and at one time McLachlan was a "front bencher" which surprised many political observers.