The inscription on the reverse reads "His R.H. the Duke of Sussex painted by Joseph Lee from the Original by Thos. Phillips, Esq., R.A. Dec. 1820".
Prince Augustus Frederick, Duke of Sussex (1773-1843), 6th son of George III, was a patron of art and science.
A "large whole length" portrait of the Duke of Sussex is recorded in Phillip's sitter book on 5 April 1828. This portrait was exhibited at the Royal Academy, London in 1828, no. 71 and the enamel copy by Lee was engraved by H. Robinson for Jerdan's National Portrait Gallery, 1831.