Crommelin, Nicholas Crommelin de Lacherois (De la Cherois) (1783–1863), gentleman and entrepreneur, was born 10 June 1783, eldest son of Samuel de Lacherois and Mary de Lacherois (née Dobbs), a niece of Francis Dobbs (qv). His father was a linen merchant in Lisburn, Co. Antrim, who after 1790 by the terms of a cousin's will took the surname Crommelin in addition to his own. On succeeding his father, Nicholas rebuilt the family house at Carrowdore, Co. Down, as a castle; the ordnance survey memoirs described it some years later as of ‘imposing proportions’ but ‘of an unfinished appearance . . . having no external plastering’. In 1821 he was high sheriff of Down, and presented George IV with an address from the county when the king visited Ireland; in 1830 he was high sheriff of Antrim. He was very prominent in the Orange order. Motivated apparently by philanthropic ideals as well as by entrepreneurial ambitions, Crommelin in 1824 began developing his estate on the Antrim plateau; he is said to have received a parliamentary grant of over £10,000 to colonise the somewhat bleak and hitherto undeveloped area, and spent large sums of his own money. He bought one townland and rented two others, and had them made into a separate parish, where he built a small village, which he called Newtown Crommelin; his vain hopes for its prosperity were fostered by his discovery in 1843 of iron ore in the area. He had it analysed and built a peat-fuelled smelter, but technical and other problems meant that the furnace, like Crommelin's improvements in his new settlement, were soon abandoned. The ore deposits were afterwards worked by Edward Benn (qv) and others. Crommelin's planned harbour at Cushendun, Co. Antrim, to be called Port Crommelin, was likewise abandoned, though approved by parliament in 1830 and shown on contemporary maps; work may never even have been begun, since Crommelin's financial affairs were in grave difficulties. His tenants owed him several thousand pounds, so that he was unable to pay the rent of Newtown Crommelin; he had to leave Carrowdore Castle and lived in the Caves House, Cushendun.
Crommelin died 28 March 1863 in Rockport, Cushendun. He married (17 December 1810) the Hon. Elizabeth Mullins, daughter of the 2nd Lord Ventry; they had three sons and four daughters. She died 12 April 1820, two months after the birth of her youngest son. A son married a daughter of Andrew Mulholland (qv); a grandson was Andrew Claude de la Cherois Crommelin (qv).