Prince William Henry, Duke of Gloucester (1743-1805), was the fifth child of Frederick, Prince of Wales and Princess Augusta of Saxe-Gotha. The portrait closely resembles a pastel portrait of the Duke painted by Francis Cotes in 1769 (RCIN 400891). The grey-blue modelling of his face gives it a slightly bruised appearance which is typical of the work of the artist, Richard Crosse. The Prince is wearing undress (ordinary, rather than ceremonial) uniform of the Grenadier Guards, of which he was appointed Colonel in 1770. In 1762, he had been installed as a Knight of the Garter, and he wears the ribbon and star of the Order here. In 1765, his sister Augusta had written that 'William is very much liked by the ladies'. William secretly married Maria Waldegrave, niece of Horace Walpole, art historian and writer, in 1766, only revealing the marriage to the King in 1772. George III did not approve, and the Duke, Duchess, and their children were barred from the royal presence until 1780.

Richard Crosse (1742-1810) was born near Cullompton, Devonshire. He was a deaf mute and took up miniature painting as a hobby, then went to London to study at Shipley's Drawing School. He was appointed Painter in Enamel to George III in 1788. He painted many leading figures of the day and was a prolific worker – in 1777 he produced about 100 miniatures. Crosse also painted a miniature of the Duke's brother, Henry Frederick, Duke of Cumberland (RCIN 421968) and exhibited them both at the Royal Academy in 1771.