William Frederick (1776-1834) is wearing the star of the Order of the Garter. He was the only son of William Henry, first Duke of Gloucester and Edinburgh (1743–1805), and his wife Maria, Countess Dowager of Waldegrave. He was born at the Teodoli Palace in Rome, attended Trinity College in Cambridge and was elected a fellow of the Royal Society in 1797 and chancellor of the University of Cambridge in 1811. William entered the army at the age of 13 and had a distinguished career, serving in Flanders from 1794 to 1799 and becoming Field Marshal in 1816. In the same year he married his cousin, Princess Mary (1776–1857). They had no children. William took little part in politics, but supported the abolition of slavery both in parliament and as president of the African Institution. He also supported Catholic emancipation. He died at his home, Bagshot Park in Surrey, and was buried in St George's Chapel, Windsor.

This portrait may be an adaptation of a drawing by Abraham Wivell, made during the celebrated ‘trial’ of Queen Caroline in 1821, part of her husband’s attempt to divorce her, and engraved by James Thomson in 1822.

Giovanni Trossarelli (active early nineteenth century) was the eldest son of Francesco Trossarelli, a miniature painter from Turin. Giovanni settled in London around 1790. He exhibited at the Royal Academy between 1793 and 1825, including a miniature of Prince William of Gloucester in 1793. He taught drawing to the duchess of Gloucester and painted many members of the royal family.

The miniature is inscribed on the back in ink: William Frederick Duke of Gloucester by Trossarelli married to Princess Mary Eleventh Child of K. George 3.