The casket, in the manner of the Valadie workshops, is decorated with panels of agate, heliotrope and lapis lazuli.
The sides have chiselled urns and scrolling acanthus supported by cherubim; the corners with grotesque masks and scroll feet.
The lid has a rectangular gilt-silver relief of putti teasing a goat, after Duquesnoy, and there is a shield with monogram on the back.
It was probably designed for a christening robe, 34.3cm.
Francois Duquesnoy (1597-1643) was a Flemish Baroque sculptor who worked mostly in Rome. Several copies were made of his bas-relief of putti playing with a male goat, which became popular with Dutch artists.
The casket previously belonged to William Beckford (1760-1844) who became an art collector on a massive scale after inheriting a vast fortune in 1770.
In 1823, his collection was dispersed in a great sale, at which Brownlow, 2nd Marquess of Exeter (1795-1867) purchased the casket.