His father, the third son of Sir William Douglas, 4th Baronet of Kelhead, was a brother of the sixth and seventh Marquesses of Queensberry.

Douglas' father died in 1837 and his mother in 1833 (burial records of the church of St Mary-Le-Bone, London), he was educated at Edinburgh Academy, Rugby 1843-47 and Durham University where he graduated B.A.

[2] Douglas arrived in New South Wales with his brother Edward in 1851 and was appointed a gold-fields commissioner, but gave this up to enter on a pastoral life.

Douglas was elected member for the Darling Downs and afterwards for Camden in the New South Wales Legislative Assembly until resigning on 17 July 1861.

After the death of Sir Peter Scratchley in December 1885 Douglas acted as special commissioner for the protectorate of British New Guinea for nearly three years (1886–88), and showed tact and ability in his dealings with the local inhabitants.

William West Simpson, who was killed in a carriage accident 23 November 1876, and for the second time in 1877 to Sarah, daughter of Michael Hickey, with whom he had four sons: Douglas died on 23 July 1904 at Thursday Island.