This site contains Engineering Instructions, Diagrams, Specifications and support articles, concerning the various types of clock used by the British G.P.O. (General Post Office).

Types of clock covered are:-
Master clock system (Clock 12, 16, 24, 36 & 46)
Clock Electronic 1A System
Synchronous (mains electricity powered)
Speaking Clock
Radial Time Recorders
Watchman's Tell Tale Clock