English 18K gold watch with duplex escapement Circa 1828

An English 18K gold key wind open faced pocket watch with duplex escapement, London Hallmark for 1828. Gilt full plate movement, duplex escapement, 3-arm balance, diamond end stone. White enamel dial, black Roman numerals, black outer minute track, subsidiary seconds at 6 and gilt spade hands. 18 carat polished consular case, engine turned band, inner cap. Dial and movement signed, case stamped ‘RM’.
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Diameter: 51 mm
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Signed: Cockburn Richmond