English precision lever with one minute tourbillon Circa 1910

Gold open faced double roller lever with one minute tourbillon
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An important, oversized and extremely heavy English open faced 18 carat gold precision pocket watch with one minute tourbillon and double roller lever escapement, circa 1910. Glazed, frosted gilt 3/4 plate movement, ébauche: Nicole Nielsen, raised barrel engraved with honour cyphers, gold chatoned centre wheel, finely polished three armed steel tourbillon cage of Nielsen type 1 with polished screws, lever escapement with a counter poised gold weight, Guillaume gold screwed compensation balance. Off-white enamel dial with Roman numerals, auxiliary seconds and blued spade hands.  Plain case, casemaker’s punch mark HMF for Harrison Mill Frodsham, turnable pendant. Dial signed, movement signed and numbered. Accompanied by a Frodsham certificate and copies of Kew Observatory Extracts from the Archive.
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Diameter: 65 mm
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Weight: 243 g
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Signed: Charles Frodsham London
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This watch was submitted for chronometer testing at Kew Observatory in 1919 and straightaway reached the outstanding result of 88.6, awarded with the Kew A Certificate.