Beresford, William (1743–1819), 1st Baron Decies , Church of Ireland archbishop of Tuam, was born 16 April 1743, an illegitimate son of Marcus Beresford, first earl of Tyrone (1694–1763). He entered Trinity College Dublin on 18 December 1759, and there graduated BA in 1763 and MA in 1766, before becoming a clergyman.
His birth into the politically influential Beresford family afforded William a degree of opportunity, and he was made a vice-regal chaplain in 1766. Brother of George de la Poer Beresford (1735–1800), the first marquess of Waterford, he married Elizabeth Fitzgibbon, sister of the future Lord Clare (qv), on 16 June 1763; they had three sons and five daughters. However, these connections did not automatically result in his being promoted to bishop, despite reaching episcopal age in 1773, and he spent several years as a well-beneficed rector of Urney in the diocese of Derry (earning an annual salary of about £1,500 in 1776). The Beresford family complained that he was overlooked for several episcopal vacancies in the 1770s and it was not until 1780 that he was created DD and consecrated bishop of Dromore (8 April 1780). At Dromore he erected a handsome new episcopal residence. Within a couple of years he was transferred (21 May 1782) to the diocese of Ossory and, as bishop there, took his seat in the Irish parliament and exercised influence over the ecclesiastical borough of St Canice.
The death of Primate Richard Robinson (qv) in 1794 was the stimulus for a reorganisation within the Church of Ireland hierarchy, and Beresford was one of the candidates rumoured to succeed him. However, his familial ties disadvantaged him, because the government did not want to favour one Irish ‘party’ over another and he was appointed to the vacant archbishopric of Tuam instead (10 October 1794). An influential and senior position within the church, it was worth £5,000 per annum (which was more than Archbishop Charles Agar (qv) received for the archbishopric of Cashel), and provided him with extensive patronage.
In the late 1790s Beresford regularly attended parliament, particularly in the crucial session of 1799 as the Act of Union was debated, and shared his brother John's view that a union was the best means of securing the protestant interest in Ireland. In the years following the union he gained a temporal peerage, becoming 1st Baron Decies on 22 December 1812. Beresford was an amiable, kind and loquacious individual, and was patron to artists, including Gilbert Stuart (qv), who produced a portrait of him as bishop of Ossory. His long years of service within the established church also made him very wealthy: at his death he was worth £250,000. His eldest son, John Horsley-Beresford (1773–1865), inherited his temporal title on 8 September 1819, and his daughter Louisa, widow of Thomas Hope, married, by special licence, George de la Poer Beresford (1811–73) on 29 November 1832.