Decimal Day use pennies or threepenny pieces, to pay them in multiples of 6d (p, the lowest common multiple of the two systems). Bus companies (at that time many state-owned by the National Bus Company) were another exception, going decimal on Sunday 21 February. Decimal Day itself went smoothly. Criticisms included the small size of the new halfpenny coin and the fact that some traders had taken advantage of the transition to raise prices. Some used new pennies as sixpences in vending machines. After 15 February, shops continued to accept payment in old coins, but always issued change in new coins. The
Penny (Irish pre-decimal coin) Penny (Irish pre-decimal coin) The penny (1d) () coin was the third smallest denomination of the pre-decimal Irish pound, worth of a pound or of a shilling. To express an amount, penny was abbreviated to "d", e.g. 1d, from the Roman "denarius". It was introduced in 1928 to replace its British counterpart, used when all of Ireland was a constituent country of the United Kingdom. The last year of minting was 1968 and it ceased to be legal tender on 31 December 1971. The coin measured in diameter and weighed 9.45 grams. The bronze coin was made up of 95.5%