This is one of the series of forty-nine portrait miniatures (420431-420679; Royal Collection) of German and other forebears of the Hanoverian dynasty which were first recorded hanging in Queen Caroline's Closet at Kensington Palace by George Vertue in 1743. The series can be dated fairly narrowly by internal evidence to the years between 1593-7 and appears to be the work of a single as yet unidentified miniature painter who worked mainly at the Brunswick-Lüneburg court but also visited Brandenburg and other centres. The artist was a naïve successor to the tradition of German court portraiture established by Lucas Cranach the Elder (1472-1553) at the court of the Elector of Saxony at Wittenberg. Frederick William I, a son of John William, Duke of Saxe-Weimar, became Duke of Saxe-Altenburg in 1573. He was Administrator of the Electorate of Saxony from 1591 to 1601. Inscribed at the top in white: FREDERICK WILHELM H: Z: SACHSEN.