This is John Shepherd-Barron, the scottish guy who invented the first ATM. First installed 40 year ago by Barclays, it worked with Carbon 14-impregnated cheques, the same radioactive material that is used to date fossils. But fret not: not only it wasn't radioactive enough but they were soon replaced by cards and now even dogs can use them. The next step according to him:
He says that moving money around costs too much, so ATMs will disappear in just a few years. Instead, he predicts the cellphone will become our next purse for all kinds of transactions.
The ATM also brought other things, like the 4-digit PIN number. Shepherd-Barron thought that he could use his six-figure army number as his password, but his wife thought otherwise: "Over the kitchen table, she said she could only remember four figures, so because of her, four figures became the world standard."
The man who invented the cash machine [BBC News]