The site at Llantrisant was formally opened on 17 December by Her Majesty the Queen, accompanied by the Duke of Edinburgh and the Prince of Wales. They received a warm reception, with hundreds of local people turning up for the occasion, along with children from nearby schools who had been given the afternoon off to come and see the royal visitors. One particularly lucky girl, Rosamund Caddick, presented the Queen with an official bouquet of flowers, which rather unusually contained daffodils, silk leeks, mint and freshly struck coins.
The royal visitors were welcomed by the Lord Lieutenant of the County of Glamorgan, Roy Jenkins, the Chancellor of the Exchequer, and Jack James, the Deputy Master, with the Llantrisant Male Choir performing the National Anthem. After unveiling a plaque to mark the opening, the royal party were given a tour of the site. They spoke to many of the workers and each minted six new decimal coins, the Queen striking 1p pieces, the Duke of Edinburgh 1/2p pieces and the Prince of Wales 2p pieces.