This plaque is based on an engraving by Paul Pontius after Anthony Van Dyck's painting of the Blessed Hermann Joseph kneeling before an apparition of the Virgin Mary, 1630, now in the Künsthistorisches Museum, Vienna.
Charles II style toilet services and silver-gilt caskets enjoyed a renaissance in the 1820s. Possibly inspired by the famous Calverley Service of 1683 (now in the Victoria and Albert Museum), they are set with antique plaques depicting stories from classical mythology or religious scenes, as on the present example.
A similar William Elliott casket with inscription dated 3 April 1821 is illustrated in Vanessa Brett, The Sotheby's Directory of Silver, 1600-1940, no. 1252, pp. 272-73. Other related 19th century caskets and boxes include those sold at Christie's, London, 26 November 1975, lots 170-171, Christie's, New York, 29 April 1987, lot 271, and Sotheby's, London, 20 June 1974, lot 125.