The sitter was the third daughter and fifth child of Prime Minister John Stuart, 3rd Earl of Bute and his wife Mary née Wortley Montagu, making her a grandchild of the writer and traveller Lady Mary Wortley Montagu. In 1768, she married George Macartney (1737-1806), later 1st Earl Macartney, Ambassador to Russia 1764-1768, and Chief Secretary of Ireland 1775-1779. In 1792, Macartney also headed the first embassy to China. She died without children.
An identical enamel miniature of Countess Jane Macartney, formerly in the collection of C. H. Samuelson; sold Christie's, London, 9 February 1960, lot 47 (as by John Smart), is in the National Gallery of Ireland (inv. no. NGI 19264), see P. Caffrey, Treasures to Hold. Irish and English Miniatures 1650-1850 from the National Gallery of Ireland Collection, Dublin, 2000, p. 188, illustrated (as 'After John Smart, copy of a watercolour miniature').