The collection that includes this is probably at Leslie House, in Leslie, Fife.
This is her terse article from thepeerage, "Charlotte Julia Campbell F, #19029, d. 21 May 1846
Charlotte Julia Campbell was the daughter of Colonel John Campbell. She married George William Glanville, 13th Earl of Rothes, son of George Raymond Evelyn-Glanville and Jane Elizabeth Leslie, Countess of Rothes, in 1798. She died on 21 May 1846.
Her married name became Glanville."
Charlotte Campbell wears a simple dress, possibly without a distinct bodice, and 1780s coiffure in this Cosway portrait.
Keywords: Cosway, Charlotte Campbell, Campbell family, Glanville family, Countess, British, curly coiffure, ribbon headdress, square décolletage, close sleeves, earrings, clasps, jeweled bodice ornament, wrap