He was the Country then National Party member for Clarence from 1971 to 1981 and for Coffs Harbour from 1981 to 1990 in the New South Wales Legislative Assembly.
He was a farmer and company director before entering politics, and was chairman of the Bonville Boambee branch of the Country Party from 1957 to 1971, and of the electoral councils for the state seat of Raleigh (1958–70) and the federal seat of Cowper (1958–72).
He was also active in farming groups as State President of the Junior Farmers of New South Wales (1962–63) and Vice President of the New South Wales Jersey Herd Society.
[1] In 1971, following the retirement of sitting Country Party member Bill Weiley, Singleton was selected as one of two Country Party candidates for the state seat of Clarence.
Although outpolled by the Labor Party on the primary vote, the preferences of the second Country candidate and two independents gave him a fairly comfortable victory with 55.11% of the two-party-preferred result.