Dunn, James (1700–73), wine and porter merchant, of Lower Ormond Quay, Dublin, first presbyterian to represent Dublin city in parliament since the 1650s, was eldest son of William Dunn (1672–1715), merchant of Belfast. James Dunn became free of the Dublin guild of merchants (Trinity guild) by special grace in 1737, was elected to represent his guild on the lower house of Dublin corporation in 1738, and served as sheriff in 1740–41. In 1746, against the wishes of the lord mayor, he was selected by the aldermanic board to be an alderman. By 1750 he was in line by seniority to serve as lord mayor, but twice that year a majority of the aldermen failed to support him; and although selected in 1751 (and approved in the usual way by government), he declined to serve on grounds of ill-health.
In March 1758, with the backing of the Free Citizens' Society (a body called into existence by the events surrounding the parliamentary canditature of Charles Lucas (qv) in 1748–9), Dunn contested the Dublin city seat vacated by the death of Sir Samuel Cooke MP (d. 1758), having first resigned from the unpopular aldermanic board. He beat James Grattan (1711–66), recorder of Dublin, by 1,363 votes to 1,192. He contested the general election of 1761, but by then Lucas had returned to Dublin and decided to stand himself, as one of six candidates. Dunn polled well (securing some 1,000 votes), but withdrew from the contest on the tenth day of the poll, apparently to ensure that Lucas would be elected. The strategy succeeded, and won Dunn much popular acclaim. In 1759 Dunn joined the militia as colonel of the 3rd Regiment of Foot, and continued to hold the office at least till 1768.
Dunn's business career included involvement in the West Indian trade, and part-ownership of a letter-of-marque vessel during the Seven Years' War. He held office in several societies, serving as treasurer of the Society for the Relief of Widows and Children of Clergymen of the Diocese of Dublin (est. 1749) through the 1760s till his death, and also as treasurer for the Company for Carrying on the Cambrick Manufacture at Dundalk. He was a member of the Ouzel Galley and of the Dublin Society, and a subscriber to the Marine Society. Among various distinctions, he was presented with the freedom of the barber-surgeons' guild, and the bricklayers' and plasterers' guild. James Dunn died on 7 April 1773 at his residence on Lower Ormond Quay, where he had lived since 1750. In an obituary, the Dublin Journal (6–8 April 1773) commented on his ‘affluent fortune [combined with] the fairest and most upright character’.
Dunn married (in or about 1732) Grace Thwaites (1714–1801), a member of the Dublin brewing family responsible in the mid eighteenth century for perfecting the manufacture of Irish porter. (In 1743 Grace's sister Martha became the second wife of one of Col. Dunn's opponents in the 1761 election, the poplin manufacturer James Digges La Touche (qv), of the Dublin banking family.) James and Grace Dunn had nine children. The eldest of the four sons, William (d. October 1784), of St Stephen's Green and Seafield, Co. Dublin, was a banker, who married (1767) an Ulster heiress, Mary Thompson, of Greenmount, Co. Antrim, and the Danish West Indies. He was selected sheriff of Dublin in 1774, but paid a fine to avoid filling the office, and rose no higher in the civic hierarchy (he is thus not to be confused with William Dunn (d. 1791) of Bride St., Dublin, tallow chandler, sheriff 1768–9, alderman 1770, and lord mayor 1777–8). Of the five daughters, the third, Esther, married the London banker John Puget; their daughter Grace married her cousin the banker William George Digges La Touche (qv) of St Stephen's Green and Sans Souci, Co. Dublin. Some of Dunn's papers, together with a full-length oil portrait, remain in the hands of his descendants.