15 February 1971 Great Britain adopts new decimal currency

The new ½p, 1p and 2p were introduced on 15 February 1971. Within two weeks of Decimal Day, the penny (1d) and threepenny (3d) coins had left circulation. On 31 August 1971, the penny and threepence were officially withdrawn from circulation. 

After 15 February, shops continued to accept payment in old coins, but  issued change in new coins. The old coins were returned to the banks and therefore taken out of circulation.