Rare English platinum gold half hunter cased lever Circa 1912

Platinum half hunting cased watch by Jospeh White & Son
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A very rare, fine and possibly unique 18 Carat gold English free sprung lever movement in a platinum half hunter case, hallmarked London circa 1912. Spotted gold 1/2 plate keyless movement both plates, going barrel, plain cock with large diamond end stone, compensation balance with free sprung blue steel overcoil hairspring, club foot lever escapement, screwed in jewelling, escape and lever pivots with end stones. Engine turned platinum dial with subsidiary seconds, Roman numerals and blue steel seconds hand and gold spade hands. Substantial, plain case with blue enamel chapter ring fixed by three screws. Gold bow and winding button.
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Diameter: 51 mm
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Weight: 150 g
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Signed: Joseph White & Son Coventry Makers to the Admiralty