In the early 19th century, a man named William McClintock was one of the principals in a trading house formed in Londonderry by name of Messrs. A. Schoales, W. M’Clintock and Company. A. Schoales was probably Adam Schoales. In April 1817, Schoales and McClintock were in correspondence with Stephen Pellett of the Broadford Works, Aberdeen, regarding ‘the dirty slovenly state’ of the flax trade , as reported in the ‘Minutes of the Trustees of the Linen and Hempen Manufacturers of Ireland’ (May-July 1817), p. 5-8.
In April 1823, William was among over a dozen linen merchants and bleachers in Londonderry who requested a meeting to consider a House of Commons bill proposing the removal of transit duty on foreign linen. William was dead within six months, as reported in the Belfast Commercial Chronicle of Saturday 29 November 1823, p. 3:
‘On Saturday morning last, of putrid fever, William M’Clintock, Esq. of the House of Messrs. A. Schoales, W, M’Clintock, and Co. of Londonderry, a Gentleman in whom there was a rare combination of the social virtues, among which strict probity and an unalterable attachment to his friend were not the least conspicuous.’
Schoales and M’Clintock was still in business as late as 1836, running steamers to Glasgow, via Portrush, Campbelltown and Greenock, as per an advert for the Glen Albyn in the Londonderry Sentinel of 17 December 1836, here.