Campbell, Thomas (1733–95), Church of Ireland clergyman and miscellaneous writer, was born at Glack, Co. Tyrone, on 4 May 1733, the eldest son of the Rev. Moses Campbell (1695?–1772) and his wife, Elizabeth (née Johnston) of Tully, Co. Monaghan. He entered TCD in 1752, graduated BA in 1756, was ordained in the Church of Ireland in 1761, and obtained the degree of LLD in 1772. Some minor clerical preferments were followed by the chancellorship of St Macartan's, Clogher, in February 1773.
Between 1775 and 1793 he paid seven visits to England, during which he moved in Dr Johnson's circle. His journal of one of these visits, a valuable piece of Johnsoniana, remained unpublished until it appeared in Sydney in 1854 as A diary of a visit to England in 1775 (new ed., Cambridge, 1947). He visited France in 1787. During his lifetime he was best known for his authorship of A philosophical survey of the south of Ireland (1777). Partly a narrative of a tour of Ireland made on horseback between July and November 1775, partly a disquisition on Irish life, it was intended to enlighten the English about Ireland. A philosophical survey deals with antiquities, architecture, fashion and the economy, has three pages on Turlough Carolan (qv), takes issue with Charles Vallancey (qv) and Charles O'Conor (qv) over round towers, and advocates political and commercial union between Ireland and Great Britain. Campbell was also the author of two pamphlets, The first lines of Ireland's interest (1779) on current affairs, and A remedy for the distilleries of Ireland (1783), a denunciation of what he believed to be unfair excise taxes. A much larger work by Campbell was Strictures on the ecclesiastical and literary history of Ireland from the most ancient times till the introduction of the Roman ritual . . . by Henry II . . . also an historical sketch of the constitution and government of Ireland . . . to the year 1783 (1789). He contributed on Ireland to Richard Gough's revision of Camden's Britannia and wrote part of the ‘Memoir’ by Thomas Percy (qv) of Oliver Goldsmith (qv), a London acquaintance.
Thomas Campbell was highly regarded as a preacher and some of his sermons were published. He resided in Co. Monaghan, at Shanco near Killeevan (part of the parish of Galloon, of which, as chancellor, he was the incumbent). Beside his house he built a church in the early 1790s. He may have married Jane Holmes of Moyare, Pomeroy, Co. Tyrone, but if so she long predeceased him and there were no children. He died 20 June 1795 in London. His manuscript journal passed to his nephew, John Thomas Campbell (1770?–1830), secretary to the government of New South Wales, after whose death it was discovered in a courthouse in Sydney and edited and published by Samuel Raymond.