Decimal Day (Irish: Lá Deachúil) in the United Kingdom and in Ireland was Monday 15 February 1971, the day on which each country decimalised its respective £sd currency of pounds, shillings, and pence.
Before this date, both the British pound sterling and the Irish pound (symbol "£") were subdivided into 20 shillings, each of 12 (old) pence, a total of 240 pence. With decimalisation, the pound kept its old value and name in each currency, but the shilling was abolished, and the pound was divided into 100 new pence (abbreviated to "p"). In the UK, the new coins initially featured the word “new”, but in due course this was dropped.