Thomas Jackson Mortimer of London was active 1818-1839 and like his relatives made high end flintlock and early percussion firearms. This dueling pistol has an approximately .50 caliber smoothbore barrel with heavily coned muzzle to aid in loading. The Damascus barrel has a niter blue, dovetailed blade front sight, "21 St James's Stt London" engraved on top surrounded by scroll ornamentation, London proofs on the bottom, and a platinum "TJ/MORTIMER" maker's cartouche on the breech plug along with a platinum vent liner and band. The standing breech has an integral notch rear sight and a sighting groove in the tang along with floral engraving. The advanced, rainproof lock has "Mortimer/St James's St" signed below the pan, frizzen spring roller, sliding safety, floral engraving, and reinforced goose-neck cock with "a" cutout. The forend cap, wedge escutcheons, and wrist escutcheon are silver. The ramrod entry pipe, adjustable single set trigger, trigger plate, and trigger guard are blued, and the latter has a spur and floral and martial engraving. The trigger plate has a pineapple style finial. The pommel plate is engraved with floral patterns. The half-length stock has a checkered wrist and flared pommel.