Millar was born on 15 June 1925 in Norwood, South Australia, the son of Elsie (née Klaebe) and Percival John Turbill.

He transferred to the Department of Immigration in 1948, then in 1950 left the public service and moved to Biloela, Queensland, where he operated a dairy farm alongside his brother and stepfather.

The farm experienced financial difficulties and after five years Millar moved to Brisbane where he found work as a real estate agent.

He became "an innovative farmer, practising soil conservation and strip grazing, and improving his herd by artificial insemination", and also obtaining a pilot's licence.

[2] Millar was elected chairman of the Country Party's Kilkivan branch in 1974, having previously held office in state and federal electorate councils.