Ensor, John (d. 1787), architect and developer, travelled as a young man from Coventry, England, to Ireland in the 1730s with his younger brother George. Their parents are said to have been Job Ensor and his wife Mary Hill. John was associated with Richard Castle (qv) from 1734, and by 1743 was his clerk and measurer. He assisted him with the TCD printing house (1734) and the bishop's palace, Waterford (1749). In the late 1740s and early 1750s he (among others) was implicated in the scandal following a parliamentary investigation into corruption in the government programme of building and repairing barracks. John, as contractor for the building of the Carrick-on-Shannon barracks, Co. Leitrim (1748), was criticised for poor workmanship, denounced for gross prevarication in his evidence given before the parliamentary committee, and committed to Newgate gaol (1752).
On Castle's death (1751), Ensor inherited part of his practice and became one of Dublin's leading architects. He executed Castle's plans, with modifications, for the Lying-in (Rotunda) Hospital (1751–7). In 1764 to the east of the hospital, he designed the Rotunda (since 1919 housing a cinema), which gave its name to the hospital and was later modified by James Gandon (qv); with a fine interior, a flat ceiling, and no central supports, it was the largest room in Dublin, accommodated 2,000 people, and became the most important musical venue in the city. In the hospital pleasure gardens, he designed the loggia that sheltered the musicians, and the terrace called the ‘orchestra’ (1763), where they played to fashionable audiences to raise funds for the hospital.
Ensor contributed significantly to the development of domestic architecture, helping to transform Dublin into an elegant Georgian city with its squares and streets of characteristic red-brick houses. He planned Cavendish St. (1755), which became part of Rutland (Parnell) Square, for Dr Bartholomew Mosse (qv); the second earliest of the great Dublin squares (completed 1770s) and containing some of the finest houses in the city, several built by Ensor, it housed more grandees by 1787 than anywhere else in Dublin. In 1762 Ensor was commissioned by Lord Fitzwilliam (1711–76) to lay out the north side of Merrion Square, Dublin's second largest square, and Denzil (Fenian) St., Clare St., and Holles St.; he also laid out Gardiner's Row for Luke Gardiner II (qv) in 1765. As a speculative builder-architect, he leased sites north and south of the River Liffey, and built Doneraile House, Kildare St. (1748–53, drawings held in the IAA), and houses at 47 St Stephen's Green (1769), and 7 and 8 Hume St. (c.1770). Northland House, Dawson St. (c.1770), has been attributed to Ensor by Maurice Craig; built for the Knox family of Dungannon, it was acquired by the RIA in 1852. Ensor's last address was 89 Charlotte St., Dublin. He died in 1787. He is said to have married Elizabeth Sycan (née Waller), and to have had an only son.
His brother George Ensor (d. 1803), architect, was clerk of the works under A. J. Nevill (qv), surveyor-general, Dublin castle (1744–51), and was probably responsible for government designs during that period, which included the rebuilding of the castle. He was discharged (1851) by Nevill for taking bribes from contractors in the barracks-building programme. He won a prize from the Dublin Society (1745) for his small house design; Richard Castle was one of the judges. He may have designed several houses for his brother John; they collaborated in the design and building of the court house and market house in Roscommon (1762). In Dublin, George designed houses in Merrion Square and rebuilt the Church of St John, Fishamble St. (1766–9, demolished 1884). The latter is his most distinguished work; designed with a classical facade, it can be seen in engravings. He built the Ranelagh endowed schools in Athlone, Co. Westmeath, and Roscommon; in Armagh, he designed the county infirmary (1767) and a terrace of seven houses, nos 45–55 in Lower English St. (1768–70).
He married (11 October 1760) Sarah Clarke, heiress to Ardress House, Co. Armagh, which he transformed from a simple seventeenth-century farmhouse into a graceful Georgian country house, doubling its size, adding a portico, and creating a magnificent drawing room, decorated by Michael Stapleton (qv), Ireland's leading stuccodore. He settled in Ardress (1778 × 1783), retired in 1783, and lived there as a country gentleman till his death in 1803. Of his five sons the eldest, George Ensor (qv), barrister and writer, extended the house, which was sold to the National Trust of Northern Ireland (1960) by Capt. Charles Howard Ensor (d. 1963), DL, OBE.