Elizabeth of Great Britain (1770-1840), daughter of George III of the United Kingdom and his wife Charlotte of Mecklenburg-Strelitz. She was married to Friedrich of Hesse-Homburg and they had no children.
This portrait is the masterpiece of Gainsborough's early years. It was painted after his return home from London to Suffolk in 1748, soon after the marriage of Robert Andrews of the Auberies and Frances Carter of Ballingdon House, near Sudbury, in November of that year. http://www.nationalgallery.org.uk/paintings/thomas-gainsborough-mr-and-mrs-andrews
Thomas Gainsborough, The Painter’s Daughters with a Cat, c.1760-61, oil on canvas, The National Gallery Here are Mary and Margaret Gainsborough, aged between 9 and 10, and 8 and 9 respectively. The somewhat vicious-looking cat, referenced in the painting’s title, has been left unfinished. Here they are again, those gorgeous little girls. How lovely he sees them.