Good black slate and green marble two train clock garniture, the movement with outside countwheel

Good black slate and green marble two train clock garniture, the movement with outside countwheel striking on a bell, the 4.5" cream chapter ring enclosing a recessed gilded centre with visible escapement, signed Boniface..., within a drumhead casing over an Ellicott pendulum supported upon scroll supports and a stepped base, 18.5" high, flanked by two pedestal stepped urns, 11.5" high