Forty years ago, Britain "went decimal". Two thousand years of everyday currency history was overthrown overnight as the country woke up to "new money" on February 15th 1971 and said goodbye to coins such as the crown, the florin and the shilling.
Few economic events have affected the entire country so immediately and Peter Day delves into the archives to examine how the country prepared for and responded to D Day. It was Harold Wilson's Labour government that began the process of decimalisation in the 1960s after many years of discussion. Then cabinet minister Tony Benn recalls how changing Britain's money fitted in with the modernising ideology of the time, while former Chief Secretary to the Treasury Dick Taverne remembers the passion of the "Save our Sixpence" campaign.
Economists Peter Jay and Will Hutton discuss whether decimalisation contributed to the double-digit inflation of the 1970s alongside archive stories of price rises and "rounding up", as earnest commentators worried about how 'the housewife' would cope. Did we lose something, culturally and intellectually, when we embraced new money?
Oxford Professor of Mathematics Marcus du Sautoy considers whether "thinking in tens" is really the best way to go about things. And Peter visits The Kings' Head pub in North London where the landlord's tills charged in pounds, shillings and pence for some three decades after D-Day. He also talks to Sir Patrick Moore - patron of the Metric Martyrs campaign - about his love of imperial measures.
Britain may have been successful in decimalising its currency in 1971 but why was the movement towards full metrication - begun at the same time - never completed? Finally Peter asks, if you're old enough to remember, is it still possible to think in "old money"?
Producers: Simon Jacobs and Phil Smith
A Unique production for BBC Radio 4.
Peter Day considers the events and impact of Britain's currency going decimal in 1971.