The writing was on the wall for the GPO's army of 50,000 telephone operators when the first public phone box with automated 'trunk call' dialling was introduced on September 5th, 1959.
Ten months previously the first 'direct dial' phones had been introduced in around 18,000 private homes and businesses, with both systems being trialled in the Bristol area ready for a rollout to the rest of the UK over the following years. It was estimated that by 1970 the number of GPO telephone operators would be halved, saving an estimated £15m per year.
Before 1958, using a phone for long distance 'trunk calls' meant picking up the receiver and speaking to 'the operator' at the local exchange, who would then connect you to the number you wanted. Public call boxes used the "Button A and Button B" system first introduced in 1925.
To use one these public phones (pictured) you had to first feed the correct coins into a holding slot at the top of the box. This connected you to the operator who would instruct you to push Button A to deposit the coins and then try to connect your call for you. If the call could not be connected or went unanswered, you pushed Button B to get your coins back.
The new and streamlined coin call boxes did away with the 'pre-payment' system and the need for an operator, although the caller had to know the full number, including the area code, of the person they wanted to speak to. In the new public call boxes, you would lift the receiver and dial the number yourself. Only when the call was answered did you push your money into the coin box, which had slots for 3d, 6d and 1s pieces.
When the time paid for was running out, a series of pips alerted the caller, who could either close the conversation or insert more money to continue talking. "That's the pips so I'll have to go now" soon became a common phrase in Britain's iconic red telephone boxes.
The first call in one of the newly equipped phone boxes was made on September 5th, 1959, when the Deputy Lord Mayor of Bristol phoned the Lord Mayor of London, dialling the number himself without any need for an operator.
The new direct dial coin boxes were part of Postmaster General Ernest Marples' £35m scheme to modernise the UK's phone system and make using the telephone easier and more popular. He described the new system as "quite revolutionary" and "good value for money".
As predicted, the new technology was quickly rolled out to other areas. In 1976 the UK's last manual telephone exchange – located at Portree on the Isle of Skye – was closed, making the British telephone system fully automatic. British Telecom (BT) took over the running of the telephone system from the Post Office in 1981.
Today public call boxes are an increasingly rare sight on British streets, thanks to the rise of mobile phones. However, they still play a vital role in some remote areas where mobile phone coverage is unreliable or non-existent.