English gold pocket watch with ruby duplex escapement Circa 1808

Gold open faced duplex pocket watch 
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A fine English, 18K gold pocket watch with ruby duplex escapement, circa 1808. A polished case with master mark IM, spring-loaded covers, pushbutton at 3.30 to open back cover, at 2.30 the bezel, the back cover with faintly engraved initials. White enamel dial, Breguet numerals, outer minute track, blued steel pierced heart hands. A full plate movement, fire gilded, fusee and chain, Harrison’s maintaining power, ruby duplex escapement with ruby rest, balance and escape wheel jewelled and capped with diamond endstone on the balance top pivot, 3-arm steel balance, blued steel flat balance spring, single-footed cock with six spokes, silver regulator dial. Dial and movement signed.
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Diameter: 50 mm
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Signed: Vulliamy  London
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Benjamin Louis Vulliamy, the third-generation clockmaker, was Clockmaker to George III, inheriting the title from his father.
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The Vulliamy Cryptic Code: The signature “Vulliamy” on its own was used between 1792 – 1854. The mysterious cryptic numbering code such as “cxx” used on the present watch has been a puzzle to horological historians for many years. An attempt to decipher this code was made by Vaudrey Mercer.