A George III silver lion mask mount

A George III silver lion mask mount, by R. Johnston, London 1810, the lion mask with a ring attachment and mounted on a circular plaque, later pin brooch to back, diameter 4.4cm, approx. weight 1.4oz. For maker's mark see Arthur Grimwade, London Goldsmiths, 1990 edition, page 170, where the maker's mark is mentioned as being found on a sword in 1809.