Davenport identifies these stamps as those of Marcus Trevor 1st Viscount Dungannon. Both arms and crest belonged to the Welsh hero Tudor Trevor, and are used by his descendants. Because surnames are a recent introduction in Wales, various branches of the family have different surnames. Papworth's Ordinary lists a good number, among them Davies of London and Shropshire, Davis of Denbighshire and Dymock of Warwickshire, granted in 1581 and Dymock of Penley Hall in Flintshire. The initials I D would fit any of these families. That of the Viscounts Dungannon do not offer anyone whose name began with I or J.