Slim three-quarter plate fusee movement, the 10-size hollow-back frame nicely finished but never engraved for its retailer. Massey detached lever escapement with type-1 steel roller. Steel balance, spiral balance-spring. One-piece cream enamel dial. 45 mm diameter, 8 mm deep, not including centre arbor.
NB: Three-quarter and half-plate frames started to appear in English work from around 1820-25, though they were not to become common until much later. One would have expected jewelled rollers by the time they began to be used, although it may be that this movement is closer to 1820 when type-1 rollers were still being fitted. Whatever the explanation, this combination is very rare, being only the second example I have seen in fifty years.
No hands and edge chips to the dial. Otherwise in fine clean unbroken condition, but needing a service and fresh oil to work properly.