Decimal Day

On 15 February 1971, known as Decimal Day, the United Kingdom and Ireland decimalised their currencies.

Under the old currency of pounds, shillings and pence, the pound was made up of 240 pence (denoted by the letter d for Latin denarius and now referred to as "old pence"), with 12 pence in a shilling and 20 shillings (denoted by s for Latin solidus) in a pound.

The loss of value of the currency meant that the "old" penny, with the same diameter as the US half-dollar, was of relatively slight value, while the farthing, which was worth one-quarter of an old penny, had been demonetised on 1 January 1961.

The Coinage Act of 1792 had officially authorized the United States as the first English-speaking nation to have decimalised currency, although Tsar Peter the Great used the concept for the Russian ruble close to a century earlier, in 1704, while China has used such a decimal system for at least 2000 years. The United Kingdom's Parliament rejected Sir John Wrottesley's proposals to decimalise sterling in 1824, which was prompted by the introduction in 1795 of the decimal French franc. After this defeat, little practical progress towards decimalisation was made for over a century, with the exception of the two-shilling silver florin (worth 1/10 of a pound) first issued in 1849. A double florin or four-shilling piece was a further step in that direction but failed to gain acceptance and was struck only from 1887 to 1890.

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