On 1 March 1966, the then Chancellor of the Exchequer, James Callaghan, announced that pounds, shillings and pence would be replaced by a new decimal currency. In order for the United Kingdom to go decimal, it would need to strike billions of new coins, therefore a decision was made to move The Royal Mint from its cramped and dated Tower Hill site to a larger and more modern facility in Llantrisant, South Wales, where it has thrived ever since. In preparation for Decimal Day, which took place on 15 February 1971, 2,000 million decimal coins were struck in Llantrisant, ensuring there would be no risk of a shortage.

Comprising a halfpenny, 1p, 2p, 5p and 10p coin, these special sets were issued to the public to help familiarise them with the new decimal currency.