The sitter was the second son of Jérôme Bonaparte, King of Westphalia. His unusual nickname 'Plon Plon' derives from his pronunciation of his name when he was a child.
A signed variant, part of a bracelet containing five enamels of the sitter's family, is at Malmaison (illustrated in N. Hubert and A. Pougetoux, Châteaux de Malmaison et de Bois-Préau [...], Paris, 1989, p. 234).