Mary Ann Thynne (1778–1863) was the daughter of Thomas Master, MP for Cirencester. In 1801 she married John Thynne, later 3rd Baron Carteret of Hawnes (1772–1849), who was the third son of Thomas Thynne, 1st Marquess of Bath and Lady Elizabeth Cavendish-Bentinck, of Longleat, Wiltshire. John Thynne was Vice Chamberlain of the Household at the court of George III and Mary Ann was appointed Lady of the Bedchamber to Princess Charlotte from 1815, until the princess's death in 1817. Mary Ann Thynne was evidently a skilled and sensitive watercolourist. There are two decorated ivory boxes by her in the Museum of Fine Arts, Houston.
Mary Ann's nieces included Charlotte Anne Thynne (1811–1895), who married Walter Francis Montagu Douglas Scott, 5th Duke of Buccleuch, 7th Duke of Queensberry (1806–1844), and Louisa Thynne (1801–1859), wife of Henry Lascelles, 3rd Earl of Harewood (1797–1857). Consequently, she spent time at the estates of some of the most powerful and wealthy aristocrats in Britain, of which her sketches provide a unique record.
