Created for people who wanted to know the time and did not have a watch or clock to hand, the clock was initially only available in the London directory area, with the first British Speaking Clock introduced on July 24, 1936.
The Speaking Clock was designed and constructed at the Post Office Engineering Research Station at Dollis Hill in North London. The time announcements were automatically co-ordinated on the hour with Greenwich meantime signals.
In order to access the service, subscribers would dial the first three letters of the word 'time (dials at the time included letters as well as numbers to aid automatic calls)'. Dialling T. I. M. led to its common name 'TIM'. The service went national six years later.
Today, more than 70 million calls every year are made to the service, now officially called “Timeline”. People dial 123 in the UK to hear the modern service and calls cost 30p per minute. The timing of ITV TV programmes is still synchronised to the clock.