In 2007 to celebrate the Diamond Wedding of Queen Elizabeth II and Prince Philip, the Royal Mint released a very Limited Issue Diamond Wedding Piedfort £5 Five Pound Platinum Proof Coin struck in solid fine 999.5 Platinum weighing three ounces of pure Platinum Certified Slabbed and Graded by PCGS as PR69 DCAM with special NFC Anti-Counterfeiting Technology.
The conjoint portrait on the obverse has been created by Ian Rank Broadley, while the reverse is the work of Emma Noble and incorporates the famous coin legend TUEATUR UNITA DEUS (May God Guard These United).
These legal tender coins have been struck to proof quality using specially prepared dies and highly polished blanks.
Piedforts are coins which have been especially struck on thicker than normal blanks.
As their name suggests they are closely associated with France, where from the twelfth century they were apparently issued by the Kings as presentation pieces.
In Britain the practise of striking piedforts is later and less frequent, but medieval and Tudor examples are known.