The only genealogical information I can find shows that Frances married Francis - Frances “Fanny” (1759–1806) ∞ 1785 Francis Willock (1759–1829), son of Alexander Willock."
From Pinterest search; spots and paint crack flaws removed with Photoshop.
Mrs. Willock wears a fashionable curly very bouffant coiffure, a fichu, and wide lapels. The waist band, tight sleeves, and tight waistline suggest she may not be wearing a jacket and that the wide lapels could just be ornamental.
Keywords: Humphrey, Frances Gore, Fanny Gore, Frances Willock, Gore family, Willock family, British, bouffant curly coiffure, fichu, bows, fitted bodice, square neckline, fitted jacket, lapels, long tight sleeves, frogging, buttons, waist band, full skirt