Sir William MacBean George Colebrooke was born on 9 November 1787 in Charlton, Kent, England, son of Lieutenant-Colonel Paulet Welbore Colebrooke, Royal Artillery, and a Miss Grant. Colebrook entered the Royal Military Academy at Woolwich and in 1803, at the age of 15, was commissioned a lieutenant in the Royal Artillery. From 1805 to 1809, he served mainly in Ceylon and from 1809 to 1810 in India. The next year he went to Java, and in 1813 was a member of a mission to Sumatra.

In 1820, Colebrooke married his cousin Emma Sophia Colebrooke, and they had three daughters. The following year Colebrooke returned to England, and in January 1823 was appointed to the Commission of Eastern Enquiry. The work of this royal commission took Colebrooke to the Cape of Good Hope (Republic of South Africa) from 1823 to 1826 and to Mauritius in 1827 and 1828, but its most significant achievements were in Ceylon. After conducting extensive investigations there from 1829 to 1831, Colebrooke returned to Britain and produced in 1831 and 1832 a series of reports advocating far-reaching social, economic, and political reforms. In September 1834, Colebrooke became lieutenant governor of the Bahamas, where he served from 1835 until 1837, where he became governor general of the Leeward Islands. In July 1840 he left Antigua and after an extended leave was appointed lieutenant governor of New Brunswick on 26 March 1841. In April 1848, Colebrook left New Brunswick to become governor and commander-in-chief of British Guiana (Guyana), a post he held only briefly before transferring to a similar position in Barbados in August 1848. He served there with distinction until 1856 and then returned to service with the army, rising to the rank of general in 1865. On 6 February 1870 Colebrooke died at his home in Salthill, near Slough, Buckinghamshire, England.

Source: Dictionary of Canadian Biography.