The convenience of being able to withdraw money from your account anywhere in your city — or anywhere in the world for that matter — came from the inconvenience of John Shepherd-Barron, who during a bath one day figured out a way to do just that. As he recalled in a BBC interview in 1994 “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.”

On this day, June 27, in 1967, Shepherd-Barron’s invention, the world’s first automated teller machine was installed in a branch of Barclays bank in Enfield, north London.

The ATM magnetic-strip cards had yet to be invented at the time, and the ATM machine used checks impregnated with carbon-14, a mildly radioactive substance. Not enough to cause any harm, but enough to be detectable by the machine, which would match the check against the pin number. As for that pin — that too was a invention of Shepherd-Barron’s, a by-product of the ATM. He could remember the six digits of his army number, but decided to check with his wife how many she could easily remember. “Over the kitchen table, she said she could only remember four figures, so because of her, four figures became the world standard,” he laughed.