English important gold high quality chronometer watch Circa 1810

Gold open faced watch by Brockbanks
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A heavy English 18 carat gold pocket chronometer by important chronometer maker Brockbanks London, circa 1810. Full plate movement, chain/fusee, adjustable spring chronometer escapement, bimetallic chronometer balance with 6 screws and 2 trapezoidal sliding weights, polished steel chronometer escape wheel, blued balance spring, diamond endstone, splendidly decorated cock, plate signed and numbered. Polished 18carat pink gold pair case with matching London Hallmarks from 1810, maker’s mark WM, and original dome. Signed enamel dial with Roman radial hours, outer minutes track, subsidiary dial for the seconds, and gold hands.
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Diameter: 57 mm
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Weight: 165 g
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Signed: Brockbanks London
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This rare pocket chronometer is in excellent original condition. 
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Brockbanks – This is how the brothers John and Myles Brockbank from London signed their watches; mainly excellent pocket and marine chronometers. They were excellent chronometer makers from the early days of chronometer construction. Both were members of the Clockmakers Company. Their best known employees were at times Thomas Earnshaw and Peto, who developed a variation of the spring escapement (“cross detent”). Some Brockbank chronometers with this escapement have survived and fetch high collector prices on the market. Between 1775 and 1815, the brothers Samuel Elliot Atkins joined the company and from then on traded as Brockbank & Atkins.

The case maker William Mean, maker of the present case, was working at 19 St. John Lane at the time this clock was made. His first mark was registered on April 9, 1783 at the address 8 St. John’s Street Road, the next on August 15, 1791 (7 Albemarle Street, St. John Square), the following at 19 St. John Lane on August 2, 1799 and finally, on December 1, 1818, at 2 Jerusalem Passage. All of these addresses were in a small area in eastern Clerkenwell.
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Reference 0028000