An early 19th Century 16 bore flintlock pistol

An early 19th Century 16 bore flintlock pistol, hexagonal barrel 8 in., London proof marks, the underside with barrel maker's initials 'T.A.', with hooked breech and retained to the stock by two keys, acanthus engraved tang incorporating back sight, lock signed 'WALLACE', swan necked cock, roller bearing to the frizzen spring, full stock with stocker's mark 'W. GRANT', steel furniture, the stock having and unusual and elegant taper toward the muzzle, brass tipped wooden ram rod.