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.