English gilt-brass verge with concealed erotic scene Circa 1790

Gilt-brass pair-cased verge watch
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A fine, rare and large English gilt-brass, enamel, pearl and paste-set pair-cased verge pocket watch with regulator dial, calendar and concealed erotic scene, circa 1790.
Forally engraved bezel set with alternate split-pearls and red pastes, the back decorated to match and set with a painted on enamel panel depicting two maidens with doves in the Blois manner, the inside with a polychrome enamel pastoral scene showing two young couples training for a love contest.
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White enamel regulator-type dial with Arabic numerals, outer minute track, subsidiary dials for the date, hours and seconds, gold hands. Gilt-brass full plate movement, cylindrical pillars, fusee with chain, verge escapement, plain brass three-arm balance, flat balance spring, gilt-brass English cock with diamond end-stone. Gilt-brass dust cap. Movement signed.
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Diameter: 73 mm
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Signed: John Bittleston London
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The case is slightly scratched.