Rare English silver open faced chronometer watch Circa 1818

A rare English silver open faced chronometer with Arnold’s right angle compensation curb, circa 1818. Gilt full plate movement with Arnold detent escapement, three arm steel balance, maintaining power, finely engraved balance cock, with Arnold’s adjustable right angle compensation curb. White enamel dial, Roman numerals and subsidiary seconds. Plain polished case. Movement signed. Hallmarked for London 1818, case maker’s mark ‘TH’.