Ferguson, John Stephenson (1761–1833), linen manufacturer, was the eldest son of James Ferguson (d. 29 December 1784), medical doctor, and Jane Ferguson (née Stephenson) of Belfast. His date of birth and details of his education are unknown. His father, who had other children from a previous marriage, was interested in the developing local linen industry. He received a £300 premium from the linen board for developing the bleaching process by using lime, and later showed the efficacy of sulphuric acid; a relative, Victor Ferguson ( fl. 1690), was also a medical doctor and a member of the Belfast Society, noted for his pamphlet defence of the presbyterian minster, John McBride (qv).
John Stephenson Ferguson founded a very extensive linen firm. He claimed to have exported in 1824 some 40,000 –50,000 pieces of linen; he travelled all over Ireland buying linen, and his own large bleachgreen at Ballysillan produced 23,470 pieces of linen a year. He was involved in banking, owned a papermill at Antrim, and was among the leading merchants of his day: he was president of the Belfast chamber of commerce 1821–32, a long-serving member of the committee of the Charitable Society, and a member of the committee of the Linenhall Library in 1798. He had been a member of the Volunteer Company of Belfast, but seems to have been one of those presbyterian merchants who rejected radical politics in the late 1790s; he was a member of the Yeoman Cavalry of Belfast in 1798. He married (1795) Eleanor (Ellen) Beggs, who with their three sons survived him at his death in Belfast (3 March 1833). He was buried in Clifton St. graveyard, beside the Poor House which he had helped support.