The first 'cash point' automated teller machine (ATM) was installed in Britain 40 years ago today.
The machine, installed by Barclays at its Enfield branch in London, did not use a plastic card to access accounts, but instead used radioactive cheques impregnated with a small amount of Carbon 14.
"It struck me that there must be a way I could get my own money, anywhere in the world or the UK. I hit on the idea of a chocolate bar dispenser, but replacing chocolate with cash."
Shepherd-Barron said that, although the cheques were radioactive. he had calculated that people would have to eat 136,000 of them to suffer any harm.
He decided on using a Pin for security after realising that he could easily remember his six-digit army number.
But tests conducted on his wife found that the most she could reliably remember was a four-digit number, so Shepherd-Barron standardised on that.
Shepherd-Barron was awarded an OBE for his invention in 2005.
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