This miniature was painted three years after Maria's second marriage, to William Henry, Duke of Gloucester, George III's younger brother. The marriage was kept secret and 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. Maria was the favourite niece of Horace Walpole, art historian and writer, and he described her: 'beauty itself! her face, bloom, eyes, hair, teeth and person, all are perfect'. Humphry's portraits of her children, Prince William Frederick and Princess Maria Matilda, hung in Walpole's bedroom at Strawberry Hill in London.

Ozias Humphry (1742-1810) was born in Devonshire, moved to Bath where he had rooms in the house of Thomas Linley, the musician, and then went to London where, in 1764, Sir Joshua Reynolds persuaded him to settle. Humphry spent a brief period in India (1785-7), exhibited at the Royal Academy from 1779 to 1797 and became a Royal Academician in 1791. His sight began to fail in 1792 when he turned to drawing in oil and pastel. He became blind in about 1797-8.

Signed on the right OH [monogram]. Inscribed on the back in ink, probably by the artist: Duchess of Gloucester / OH / 1769.