[3] He married Mary Taylor in Colinton in 1838 and together they emigrated to New South Wales on the ship Duncan as assisted migrants and arrived at Sydney on 30 June 1838.

William Miles died on 22 August 1887 at his home in Toowoomba, when an abscess in his ear led to an inflammation of his brain.

[4][5] He had expressed a wish to be buried in the Toowong Cemetery in Brisbane and his body in a cedar coffin was conveyed by a special black-wreathed train from Toowoomba to Brisbane, where a largely-attended Presbyterian funeral was conducted at the cemetery.

He was Colonial Secretary in the Douglas Ministry, from 15 March 1877 to 7 November 1877, when he was transferred to the Public Works Department where he was Secretary for Public Works from 7 November 1877 to 21 September 1878 when he resigned[7] and was succeeded by Sir Samuel Griffith, in whose first Ministry he was Secretary for Public Works and Mines from 13 November 1883 till his death on 22 August 1887.

[2][8] The town of Miles, Queensland is named after him; he owned a property Dulacca in that area.