Very rare English 18k gold pair cased lever watch Circa 1812

Gold lever in pair cases by Anness
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A fine, very rare English 18 carat gold pair cased lever pocket watch, Hallmarked London 1812. Hinged, frosted gilt full plate movement with cylindrical pillars, jewelled to the third, fusee and chain, Harrison’s maintaining power, rack lever escapement with large brass escape wheel, three armed steel flat rim balance with flat balance spring, diamond endstone, single footed foliate engraved cock, regulator arm with an engraved scale on the backplate. White enamel dial with Arabic numerals, outer minute divisions and original gold pear hands. Polished outer case, master mark WM for William Mean, polished inner case, gilt brass dust cap. Movement signed.
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Diameter: 52 mm
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Signed: Anness Cheapside London
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The rack lever escapement was patented by Litherland in 1791 and was used by both Liverpool and London makers during the first quarter of the 19th century. This piece is rare due to the gold pair case, as most rack lever watches were made with silver cases.