ATM Inspiration had struck Mr Shepherd-Barron, employee of the printing firm De La Rue. while he was in the bath. “It struck me there must be a way I could get my own money, anywhere in the world or the UK. I hit upon the idea of a chocolate bar dispenser, but replacing chocolate with cash.” When Shepherd-Barron took the idea to Barclays, Barclays was convinced immediately. The then chief executive signed a hurried contract with Shepherd-Barron. The world’s first ATM was installed in a branch of Barclays in Enfield, north London. Actor Reg Varney, from the television series ‘On the Buses’, was the first to withdraw cash. Shepherd-Barron’s machine used cheques that were impregnated with carbon 14, a mildly radioactive substance. The machine detected it, then matched the cheque against a Pin number. The ATMS were at that time called DACS for De La Rue Automatic Cash System.
The machine paid out a maximum of £10 a time. The first machines were vandalised, and one that was installed in Zurich in Switzerland began to malfunction mysteriously. It was later discovered that the wires from two intersecting tramlines nearby were sparking and interfering with the mechanism. One by-product of inventing the first cash machine was the concept of the Pin number. Mr Shepherd-Barron came up with the idea when he realised that he could remember his six-figure army number. But he decided to check that with his wife, Caroline. “Over the kitchen table, she said she could only remember four figures, so because of her, four figures became the world standard”.
Shepherd-Barron never patented his ATM invention, instead he decided to try to keep his technology a trade secret. The reasoning was that, applying for a patent would have involved disclosing the coding system, which in turn would have enabled criminals to work the code out.