Sibbett, Robert Mackie (1868–1941), journalist and author, was born 4 September 1868 in the townland of Killycoogan, Portglenone, Co. Antrim, the only son of James Mackie and Agnes Ann Mackie (née Sibbett; b. 1832, d. 4 November 1916), who were married on 20 November 1867. After Robert's birth James Mackie deserted his wife Agnes, who afterwards reverted to her maiden name, along with her son. Robert Mackie Sibbett attended Gortgole and Aughnacleagh national schools, gaining a love of learning and a thirst for education which he kept throughout his life. In the 1890s he travelled to America but returned to his native land and started his career in journalism with the Ballymena Weekly Telegraph, where he wrote some articles based on his experiences. In 1897 he moved to Belfast and took up a post with the Belfast News Letter, where he remained until 1920. He also wrote for the Ulster Farmers Journal and then (1921) joined the staff of the Belfast Telegraph, where he remained until his death. While on the staff of the Belfast News Letter he contributed a long series of articles to the Belfast Weekly News on the history of the Orange tradition. This became the basis for his subsequent major work.
He was a member of the Institute of Journalists, taking the post of chairman in 1917. In 1927 he was appointed one of the minute-takers at the trial for heresy of the Rev. Professor J. E. Davey (qv), in the Presbyterian Church. He was a member of two of the most influential fraternal organisations in their day, the Freemasons and the Orange Institution: he belonged to the Press Masonic Lodge 432 and Carnmoney Masonic Lodge, as well as York LOL 145 and Killycoogan LOL 1175, and was a member of the historical committee of the Grand Orange Lodge of Ireland. In 1926 he was appointed historian of the Grand Orange Council of the World.
A deeply religious man, he covered the Portstewart convention meetings every year for the Belfast Telegraph. On moving to Glengormley, he became an elder in Carnmoney presbyterian church, and was instrumental in the establishment of Glengormley presbyterian church when, with a friend, he started up religious services in the local tearooms. He remained a faithful elder and clerk of session of Glengormley presbyterian church to the end of his life. Sibbett wrote several books: The revival in Ulster. The life of a worker: William Montgomery Speers (1909); Orangeism in Ireland and throughout the empire, 1688–1828 (1914); For Christ and crown: a history of the Belfast city mission (1926); On the shining Bann (1928; reprinted 1991); Princely Ulster pedigrees (1931); and Orangeism in Ireland and throughout the empire 1688–1938 (1939). He died 23 October 1941.
He married (7 April 1909) Minnie Gibb Gamble (d. 4 August 1976), daughter of Mr James G. Gamble, FRIBA, clerk of works of the Belfast city hall. They had two sons, Robert and Wilfred, and a daughter, Beryl.