Although William Birch painted enamel miniatures of his own composition, like many enamellers he often copied existing portraits. This enamel was painted after a full length portrait by Sir Joshua Reynolds. It was completed in 1786, after the sitter’s death, when Birch was working in England and exhibiting at the Royal Academy. In 1794 he left England for Philadelphia where he continued his career and where his son Thomas also produced enamels and engravings.

Charles Watson Wentworth, Second Marquess of Rockingham poses here wearing insignia of the Order of the Garter. He was Lord of the Bedchamber to George II and George III and was appointed Lord Lieutenant of the North and East Ridings of Yorkshire. His prominent political career included being Prime Minister in 1765-66 and again in 1782 for a few weeks before his death.

Portrait miniatures in enamel became popular in the early seventeenth century and remained so well into the nineteenth century. In this technique, finely powdered glass coloured by metal oxides was applied to a metal surface and fired. Different colours required different firing temperatures, making it a long and technically demanding process. Such painstaking efforts were rewarded by the finished portrait’s glossy finish and relative durability.

Sir Arthur Gilbert and his wife Rosalinde formed one of the world’s great decorative art collections, including silver, mosaics, enamelled portrait miniatures and gold boxes. Arthur Gilbert donated his extraordinary collection to Britain in 1996.