A George III Irish 18ct gold open-faced pocket watch by Sean Houston of Dublin

A George III Irish 18ct gold open-faced pocket watch by Sean Houston of Dublin, white enamel dial with black Roman numerals and Arabic outer minutes, signed plate and diamond end stone to the foliate pierced balance cock engraved with a grotesque mask, the case with rubbed Dublin marks, maker's initials possibly AN and probably 1806, the detachable cover engraved Houston Dublin no. 373, glass missing, 4.5cm wide, 101g