'Savings with a thrill!'

In 1956, adverts enticed the British public with a brand new opportunity. Buy premium bonds for one pound, for the chance to win a thousand. At the time, it was a fortune - half the price of the average house.

Behind this tantalising dream was a machine called ERNIE - the Electronic Random Number Indicator Equipment.

ERNIE was built by the team who constructed Colossus, the code-breaking engine housed at Bletchley Park. They had just nine months to make a machine that generated random numbers using all the latest kit, from printed circuit boards to metal transistors.

In this episode, mathematician Hannah Fry talks to Dr Tilly Blyth from the Science Museum about how ERNIE became an unlikely celebrity.

Presented by Hannah Fry

Produced by Michelle Martin

Photo: ERNIE 1