February 15 1971 marked the official date the United Kingdom decimalised from its historic pounds, shillings and pence to the new system of 100 new pence to the pound. Known as Decimalisation, Decimal or simply ‘D’ Day, it ended the centuries old tradition of using 12 pence to the shilling and 20 shillings to the pound. Although work on the new system began in earnest in March 1966, new coins were gradually phased in up to D-day in 1971. In April 1968 the first of the new coins, the five and ten new pence, were introduced with equal value to the old shilling and florin coins respectively. A year later the new 50 pence coin was released, replacing the ten-shilling note. The remaining decimal coins – the one, two and halfpenny coins – were all introduced on 15 February 1971.