Jackson, Thomas (1807–90), architect, was born in Waterford city, eldest son of Anthony Jackson, a quaker and freeman of the city, who was descended from Anthony Jackson, a quaker who left Lancashire in 1649 and settled in Meath. Thomas was articled to the architect George Dymond in Bristol before moving (1829) to Belfast, at the request of Thomas Duff (qv) (c.1792–1848), a Newry architect looking to establish a Belfast office. Jackson supervised the opening of the office and was soon taken into partnership by Duff. Their most important building was the Old Museum in College Square, built (1831) as the headquarters of the Belfast Natural History and Philosophical Society. A four-storey stucco building, it followed the neo-classical lines of its neighbour, the Belfast Academical Institution. As the first building erected in Ireland by voluntary subscription, it met with great publicity and acclaim and enabled Jackson to set up his own practice in 5 Corn Market (1835). He had recently married (New Year's day 1835) Lydia Newsom Ridgeway, from a quaker family in Waterford. Around this period he probably took his younger brother, John Pim Jackson (1815–47), into his practice. John Pim later had his own offices in Lower Arthur St., but he died young, leaving two daughters.
Many of Thomas Jackson's buildings – such as the Downshire Road presbyterian church, Banbridge, Co. Down – follow the neo-classical style which was popular in nineteenth-century Belfast, but he was also innovative, capable of quickly mastering fashionable styles, and was among the first to bring the Gothic revival style of Augustus Pugin (qv) to Belfast. His Reformed Presbyterian Church in College Square North (built 1843; demolished 1966) had a conventional galleried interior but the façade was medieval. The following year he completed St Malachy's Roman Catholic church in Alfred St. His masterpiece, it has been called variously ‘one of the best Tudor revival churches in Ireland’ (Dixon, 25) and ‘a superb example of Sir Walter-Scottery at its most romantic’ (Brett, 23). Perpendicular windows and chess-rook turrets on the exterior give way to the ‘icing-sugar flamboyance of the interior, as though a wedding cake had been turned inside out’ (Brett, 23 and plate 19).
Jackson was the principal architect of the Ulster Bank buildings that were erected all over the province in the mid-nineteenth century. For these he employed the subdued Italianate manner imported from London and Sussex. The best examples still standing are in Antrim, Maghera, Strabane, Lisnaskea, and Castlederg. Although most noted for his individual buildings, Jackson was greatly preoccupied with designing suburbs and terraces, with buildings that were in harmony with each other and would contribute to the organic growth of the town. A number of his terrace designs were highly successful, especially the Royal Terrace in late Georgian style on Lisburn Road (completed 1848; demolished 1969–70). Queen's Elms (built 1859; demolished 1965) was a contrastingly sculptural composition in the Jacobean style. His attempt to design a north-west Belfast suburb, which he named Cliftonville, after a noted suburb in Bristol, was less successful: building costs rose and the houses and gardens were more cramped than he had envisaged.
By 1865 Jackson was in partnership with his eldest son, Anthony Thomas Jackson (1838–1917), and his capacity to assimilate new styles was declining. He did not favour Ruskin's high Victorian mixed style, which Anthony promoted. Riddell's Warehouse on Ann St. (completed 1867), a polychrome elevation, roofed over with iron and glass, is presumably the work of Anthony, a leader in bringing polychrome mixtures to Belfast. In 1871 the firm designed the red-brick town hall in Victoria St. The original drawings for this were judged too modest, with townspeople complaining that it was not a public building without a parapet. About two years later Anthony established his own office. Thomas Jackson was responsible for the Hospital for Sick Children, built (1878) in Queen St. in the Scottish renaissance style. He retired some time after this and died on 3 September 1890 at his residence, Altona, which he had built for himself (1864) on the Sydenham hillside. He left effects worth £9,547 and was predeceased by his wife but survived by two sons and two daughters. His son Anthony continued his practice until 1908 and died in Belfast 16 August 1917. His younger son, William Ridgeway Jackson (1840–86), engineer, emigrated to Australia, where he was responsible for the construction of Watson Bay tramway. His two daughters married two brothers, linen spinners named Greeves.