Barbour, Harold Adrian Milne (1874–1938), promoter of agricultural improvement, was born in July 1874, probably at Dunmurry, Co. Antrim, the son of John Doherty Barbour (1823–1901), a linen manufacturer, and his wife, Elizabeth. He was educated in England (at Elstree, Harrow and Oxford) before joining his family's firm, William Barbour & Sons. He eventually had several business interests and was a director of the Linen Thread Company.
What brought Barbour eminence was his long association with Horace Plunkett (qv) and the Irish Agricultural Organisation Society (IAOS, a body dedicated to improving agriculture on smaller farms), into which he threw himself after graduating, travelling the country, founding new societies and encouraging existing ones. The Barbours had already promoted the opening of a cooperative store at Lisburn (1882). For ten years Harold Barbour was chairman of the IAOS. When a separate Ulster society came into existence in 1922, he became its first president.
Barbour was a member and chairman of both Lisburn urban district council and Antrim county council. For a while, from its inception in 1921, he was a member of the Northern Ireland senate. Harold Barbour died on 24 December 1938 on a visit to Switzerland; he was cremated at Zürich and his ashes were interred at Lambeg, Co. Antrim. He married his cousin Anna, daughter of Robert Barbour of Paterson, New Jersey. They lived at Strathearne, Dunmurry, and at Belsize Road, Lisburn, Co. Antrim, and had three sons (John D., James, and Patrick) and one daughter (Elsie Smith). Harold Barbour was a younger brother of John Milne Barbour (qv) and a brother-in-law of Thomas Andrews (qv) (1873–1912).