Maria (bap. 1736 -1807) was the widow of James Waldegrave, second earl Waldegrave. She was the daughter of Sir Edward Walpole (1706–84), member of parliament for Great Yarmouth, and Dorothy Clement (c.1715–c.39). Her parents were not married. Her uncle was Horace Walpole, art historian and writer, and he described her as 'beauty itself! her face, bloom, eyes, hair, teeth and person, all are perfect'. After Waldegrave's death in 1763, Maria secretly married William Henry, Duke of Gloucester, George III's younger brother. The marriage was only revealed to the king in 1772. George did not approve, and the Duke, Duchess and their children were barred from the royal presence until 1780.

The Duchess' costume suggests that this miniature was painted in the early 1780s and the chiaroscuro effect (the contrast between light and shade) is due to the influence of Sir Joshua Reynolds.

It is thought that the artist is Samuel Shelley (1756-1808), who was born in Whitechapel, London, and entered the Royal Academy Schools in 1774. He exhibited at the Royal Academy from 1774 to 1804 and his work included oil paintings and watercolours as well as miniatures.