It measures 17in wide by 13in high (44 x 32cm) and is profusely chiselled, engraved and inlaid with a riot of cherubs, caryatids, armorial devices, fruiting cornucopia, masks, beasts and scrolling foliage.
The hinged lockplate covers the monogram PZ for the Eibar metalworker Placido Zuloaga (1834-1910), the name most often associated with the revival of the damascene technique in mid-19th century Spain.
Having taken over the management of the family business of armourers in 1859, the firm began to concentrate increasingly on luxury items, such as this, that were first seen by a wider audience at the London Exhibition in 1862. An exhibition of work from the Zuloaga workshops - 40 pieces from the holdings of Nasser D. Khalili - was held at the Victoria and Albert Museum in 1997.
Shapes' vendor, who agreed to an estimate of £10,000-£15,000, is understood to be a descendant of George Thorneycroft Sassoon (1936-2006), who lived on Mull, the scientist, author and only child of the First World War poet Siegfried Sassoon (1886-1967).
The casket was understood to have once resided at Heytesbury House in Wiltshire, where the poet lived a reclusive life in old age. The buyer was a Warwickshire dealer.
The buyer's premium was 16 per cent.