The halfpenny was first issued on what day when the United Kingdom and the Republic of Ireland decimalised their currencies?
Halfpenny (Irish decimal coin): The decimal halfpenny (⁄ p) (Irish: "leathphingin" ) coin was the smallest denomination of the Irish pound. Halfpenny (Irish decimal coin):  It was first issued when the Irish currency was decimalised on Decimal Day, 15 February 1971. Decimal Day: On 15 February 1971, known as Decimal Day, the United Kingdom and the Republic of Ireland decimalised their currencies.
15 February 1971