In 1833 John Greenshileds and his father Samuel Greenshields (1780-1851) founded the wholesale dry goods firm S. Greenshields and Son Company. By the turn of the century this firm had become the largest and oldest Canadian dry goods wholesaler and was a pioneer in domestic woolen and cotton goods manufacturing. His son Edward Black Greenshields (1850-1917) became a member of the family firm in 1869 and was its sole owner by 1893.

John was active in Montreal's business and Scottish communities. He was President of the St. Andrew's Society (1860-61) and one of the directors of the Victoria Skating Club.

In 1847 he married Elizabeth McCouloch Craw Black (1828-1890), the daughter of Reverend Edward Black (1793-1845) of Montreal. They had one son and three daughters.

Gregory & Woolsey were Quebec City-based merchants, a partnership between Robert Woolsey and George Gregory. They specialized in dry goods and did business with James Morrison.

John Gregory was born in 1751 in England and died in 1817 in Montreal. In 1773, he moved to North America, and formed a partnership with fur trader James Finlay, who had considerable experience in the field. On February 22, 1778, Gregory married Isabella Ferguson in Montreal, and they had several children. Little is known of his life as a fur trader, but he did spend some time on the Sturgeon River (Saskatchewan). In 1790, he was named one of the representatives of the North West Company at their annual meeting in Grand Portage, where the wintering partners exchanged their furs for trade goods. Gregory was elected into the Beaver Club in Montreal in 1791.