governor-in-chief of British North America in 1835–37, who alienated English- and French-speaking colonists in Canada.

Acheson entered politics in 1798 as member for Armagh in the Irish Parliament. After the union of Great Britain and Ireland (1800), he became member for Armagh in the British House of Commons, where he served until he inherited his father's title in 1807. In 1811 he entered the British House of Lords as a representative peer for Ireland; he supported the Whig policy of conciliating Ireland.

After being made lord lieutenant of Armagh in 1832 and a peer of the United Kingdom (Baron Worlingham) in 1835, Gosford was appointed governor-in-chief of British North America. He served as a royal commissioner inquiring into the state of affairs in Lower Canada (now Quebec) and recommended a policy of “conciliation without concession” toward French-Canadians. By 1837 he recognized the failure of his conciliation policy, and he resigned that November, leaving Canada beset with rebellions that demonstrated his policy's failures. In the House of Lords he unsuccessfully opposed the Act of Union (1840), which united Upper and Lower Canada (Ontario and Quebec).