Speaking Clocks were first installed in the UK in 1936 at Holborn, London with a second pair installed in Liverpool in 1942.  The clocks consisted of two units on each site, one being a standby, but both Holborn and Liverpool were wired together, via the GPO trunk network, so that if there was a complete failure at one of the sites, the other site would serve the whole country.

Holborn was also connected to the Greenwich time wires in the Faraday Building.

The output from the clocks were fed to the local Repeater Station for distribution around the country.

Speech was recorded onto an optical disc which was read by photo cells.

Amplifier and Control equipment
Pendulum Unit
Even Minutes Disc and Optical Unit
Hours and Minutes Cam Shaft
The full mechanism

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Last revised: April 15, 2022