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. He moved to Queensland in 1863. On 12 May 1863 he was elected as member for Port Curtis in the Legislative Assembly of Queensland. He resigned on 1 February 1866, in order to be appointed on to the Queensland Legislative Council, which occurred on 22 February 1866. On 1 March 1866 became postmaster-general in the first Macalister ministry. He was elected to the Legislative Assembly again as member for Eastern Downs. He took the portfolio of colonial treasurer in the second Macalister ministry in December 1866, but in May 1867 changed this position for that of secretary for public works. He was postmaster-general in the Charles Lilley ministry from December 1868 to November 1869, when he resigned to become Agent-General for Queensland in London. In 1871 Douglas returned to Queensland and became insolvent on 23 February 1872. Douglas was returned for Maryborough at the election held in 1875. He was secretary for public lands in the Thorn ministry from June 1876 until March 1877, when he became premier and was given the honour of C.M.G. His party was defeated at the election held in January 1879 and Douglas gave up politics. Lewis Adolphus Bernays claimed Douglas had more success as a clever political wire-puller behind the scenes than he had in parliament.
Later life
In 1865 Augustus Charles Gregory, Maurice Charles O'Connell and Douglas applied for a special grant of land to erect a Masonic Hall in Brisbane. This was granted on 15 January 1865. He was for some time on the literary staff of the Brisbane Courier, and in 1885 was appointed government resident and magistrate at Thursday Island. 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, and showed tact and ability in his dealings with the local inhabitants. In 1888 Douglas returned to his old position on Thursday Island. He visited England in 1902 and on his return continued his work until his death at Thursday Island.
Family
Douglas was married twice, first on 22 January 1861 to Mary Ann, daughter of the Rev. 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:
