Clocks Speaking were installed around 1937 at Holborn (London and Liverpool exchanges).  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 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

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Last revised: February 06, 2011