With silver key with engraved shield-shaped coat-of-arms upper part.
Few information is available on George Prior of Otley, Yorkshire, not to be confounded with the watchmaker George Prior, specialized in watches for the Ottoman market.
G.H. Baillie's Watchmakers & Clockmakers of the World p. 258 lists a G. Prior, Otley, late 18th century, most probably the same as the George Prior, jun. of Otley, in Yorkshire, whose invention of a clock escapement was awarded a silver medal and twenty-five Guineas. The escapement fitted for a pendulum of any length would not require any oil due to the very small friction, the detent spring, the impelling spring and the pendulum should all spring from one right line or centre. A detailed description of this movement was published in the 1810 The Repertory of Arts, Manufacturers and Agriculture consisting of original communications, specifications of patent inventions, ..., and notices of all patents granted for inventions, Volume XVI. - Second Series, pp. 337.
Clearly an inventive and talented clock and watchmaker, the present watch is obviously featuring one of his patented inventions as well. Fitted with a detent escapement, helical hairspring and Z-balance based on the inventions of the celebrated John Roger Arnold, it can be assumed that Prior wanted to participate at the ever-growing market for chronometers needed for the English merchant and naval fleets at the time.