To avoid the free-selection mania in New South Wales the family moved to Queensland, and purchased Wyaga station, near Goondiwindi in 1861.

His father died in 1885, and Gunn sold Pikedale station to the Queensland Co-operative Pastoral Co.

He managed a property until 1891 and then bought a grazing farm at Boonarga, near Talwood only to face floods, the bank crash and the long drought.

In 1907 Gunn, standing as an Independent, won the seat of Carnarvon in the Queensland Legislative Assembly.

In 1880, Gunn married Mary Anne Rattray Deuchar (died 1924)[2] and together had three sons and two daughters.