It appears to be a Marquess of Hertford livery button.tinner wrote: had this one
found in Suffolk
The crest description is in the book "Dictionary of Suffolk Crests".... The crest is on the funeral hatchment of Francis Ingram Seymour-Conway, 2nd Marquess of Hertford, 1743-1822; in the All Saints Church, in Sudbourne, Suffolk.....