Essex's enamel is copied after an unrecorded watercolour sketch by William Ross of 1849. On 8 March 1850 Maria II, Queen of Portugal, described the infant duc de Penthièvre to Queen Victoria as: 'un bien bel enfant et bien gentil et gaie' ['a very lovely child and very good-natured and cheerful'].

Pierre, duc de Penthièvre, only surviving son of François, prince de Joinville, and Françoise, daughter of Pedro I, Emperor of Brazil, was sent to Naval College at Newport, USA, in 1861 and subsequently served in the US Marines, the Portuguese Service and the French Service. He died unmarried in Paris on 17 July 1919.

Signed, dated and inscribed on the counter-enamel in black paint: Pierre d'Orléans / Duc de Penthièvre, / son of the Prince de Joinville / born nov: 4. 1845. / Painted by W. Essex Enamel / painter to Her Majesty & H.R.H. Prince Albert / after / Sir W. Ross R.A. / 1849.