This is the operating mechanism from a slave clock manufactured by Synchronome. Its principle of operation is basically the same as that of a Gent unit: see here.
The main differences in design are that the Synchronome is easier to adjust as the backstops are all screws. Although these are smaller units than the Gents, they both have the same low level, fairly unobtrusive, clunk when they operate.
Synchronome did make what they described as a silent slave, but they are harder to find.

This is a small 8 inch diameter slave unit manufactured by Synchronome. The slave mechanism employed in this clock is the same as the one illustrated above. The case is sprayed Bakelite, and the dial is aluminium on a steel dial plate.
These are a smaller version of the more common twelve inch diameter model. The larger models (Clock 64A) were the clocks in general use in most GPO telephone exchanges.