Rare English 18 carat gold keyless pocket watch Circa 1890

Gold lever pocket watch 
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A rare English, 18K gold keyless pocket watch which obtained a Kew A rating with 74.3 marks, circa 1890. Accompanied by a copy of the Kew A certificate. Made by Manoah Rhodes & Sons, Ltd, Bradford, Makers to the Admiralty. London hallmarks for 1890.
A polished case, stepped bezel and border, maker’s mark JG. Hinged gold cuvette. White enamel dial with radial Roman numerals, outer minute track, subsidiary seconds. Blued steel spade hands. A frosted gilt half-plate movement, going barrel, 15 jewels in screwed chatons, lateral lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring with double overcoil, diamond endstone, index regulator. Dial and movement signed.
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Diameter: 52 mm
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Signed: Manoah Rhodes & Sons  London
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The case is oxidized.
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Kew Observatory trials Various testing laboratories around the world were responsible for grading and testing watches. The most stringent is the Kew (Teddington) Observatory, just west of London. A standard Swiss chronometer test would last 15 days, however, the Kew test lasted 44 days. The tests consisted of observing the timekeeping of the watch in various positions and at various temperatures and awarding points for accuracy in these differing states. The eight testing positions were as follows: Pendant up – 67 degrees Dial-up – 42 degrees Pendant right – 67 degrees Dial-up – 67 degrees Pendant left – 67 degrees Dial-up – 92 degrees Pendant up – 67 degrees Dial down – 67 degrees.