Background
McMillan was born in 1904 in New Plymouth, the eldest child of Annie Gertrude Pearce and David McMillan, a dairy farmer near Stratford.
McMillan was born in 1904 in New Plymouth, the eldest child of Annie Gertrude Pearce and David McMillan, a dairy farmer near Stratford.
With the help of the Taranaki Scholarship, he could afford to study medicine at the University of Otago, from where he graduated Bachelor of Medicine Bachelor of Surgery in 1929.
He received his secondary education at Stratford Technical High School, where he was dux. He was a medical practitioner, first practising in Kurow (1929-1934) and then at 115 Highgate in Kaikorai, Dunedin (c1935-1936, after which the building was his electorate office to 1943, then again a medical practice after he had left parliament). The building was demolished after 1950 to make way for the Stuart Street extension.
McMillan became involved with the Labour Party in 1923.
In his view, good health extended beyond good medical support, but included educational, economic, and social factors. He represented the Dunedin West electorate from 1935 to 1943, when he retired.
He was Minister of Marine (1940–1941) in the First Labour Government, and was responsible for much of the social security system introduced by Labour. He was a Dunedin City Councillor for 1935–1938, 1938–1941, 1944–1947 and 1950–1951.
He twice unsuccessfully stood for the Dunedin mayoralty.
He was beaten by Andrew Henson Allen and Donald Charles Cameron in 1941 and 1944, respectively. McMillan died on 20 February 1951 at Dunedin from a heart disease.
Two years after his death, his widow became a Member of Parliament for North Dunedin, also representing the Labour Party.