Swiss gold hunting cased one minute tourbillon watch Circa 1980

Gold gentlemen’s pocket watch
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A Swiss 18 carat gold hunting cased pocket watch with one minute tourbillon made by Vacheron Constantin SA in Geneva, Circa 1980. The glazed movement with a lever escapement mounted on a one minute tourbillon carriage with a polished steel cage and Guillaume balance made in 1947. Later custom made white enamel dial with Breguet hour numerals, an outer minute track, sunk subsidiary seconds at 6 o’clock and blued spade hands. The plain case with a concealed hinge was also later custom made. Dial, case and movement signed and numbered, dial and movement with matching numbers, the case numbered twice. Comes with an Extract from the Archives, and the original black leather and suede lined pouch.
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Diameter: 62.5 mm
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Signed: Vacheron & Constantin Genève
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The case and dial were not made by Vacheron & Constantin and have been custom made to fit the movement.
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The Extract from the Vacheron Constantin Archives notes that this watch was created as a movement only and gives the year of production as 1947. Vacheron Constantin has confirmed that the case and dial of this watch were made outside of their organization and without their knowledge or involvement. It seems likely that the case and dial were produced in the late 1980s.
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A watch with similar tourbillon movement by Vacheron Constantin (numbered 464262 and also dating to 1947) is illustrated in Meis, Das Tourbillon. The summary tables within Meis’s book show that the present tourbillon movement, No. 464270, was tested at the Observatories in Geneva in 1948 and Neuchâtel in 1961, the tables further note that this watch won a First Prize.
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A tourbillon (whirlwind in English) is a mechanism to reduce the influence of gravity on the movement of a mechanical timepiece in order to increase accuracy. The Swiss-French watchmaker Abraham Louis Breguet invented the tourbillon in 1795 and received a patent for it on June 26, 1801. In a tourbillon, the escapement and balance wheel are mounted in a rotating cage to eliminate balance errors, creating a uniform weight.