Duke Ernest Frederick (1724-1800) is wearing a steel cuirass (a piece of body armour) and the star and blue ribbon of the White Eagle of Poland. He succeeded his father as duke of Saxe-Coburg-Saalfeld in 1764 and this miniature is probably based on a large-scale portrait painted to commemorate his accession. He was the great-grandfather of both Queen Victoria and Prince Albert.

In 1767, George III bought 'twenty or more Miniature or colour'd drawings copied from the German of the House of Brunswick' and this miniature was among them. They were all probably based on portraits by Johann Georg Ziesenis, the court painter who worked in Hanover, but the identity of the painter of this miniature is unknown.

Inscribed on the back in pencil: Ernst Friedrich ... the remainder is illegible.