John Mercer emigrated from Ireland in 1720. His first wife was Catherine Mason. His second wife was Anne Roy. Mercer lived at Marlborough Point. Mercer was a lawyer; when he traveled to Williamsburg for court sessions during the years 1748-1750, he lodged with the artist William Dering. On one of these trips, Dering painted Mercer.
Reference: According to John Mercer’s account book, Mercer supplied Dering with “sundry Paints cost 29/10 sterl 80 pr ct adve £2.13.9” in May 1749; and Mercer records Dering “drawing my Picture at a cost of £9.2.0” quoted in Graham Hood, Charles Bridges and William Dering: Two Virginia Painters, 1735-1750 (1978), 103. Original John Mercer Ledger, 1725-1750, fol. 100, Bucks County Historical Society, Pennsylvania.