Like many other mints, the Royal Mint issues bullion coins in precious metals, having much higher intrinsic value than their face value. The quarter ounce (1/4 oz) gold coins are denominated as Twenty-five Pounds (£25).
The coins are legal tender but are not intended for circulation. They are targeted at bullion investors or collectors who appreciate the special editions as pieces of art. The coins are typically "one-year" types usually issued in parallel with other denominations with the same reverse designs.
This gold quarter-ounce coin commemorates Prince Philip, Duke of Edinburgh, prince consort of Queen Elizabeth II.
The Royal Mint says about it:
Following the announcement of the passing of His Royal Highness The Prince Philip, Duke of Edinburgh on 9 April 2021, many reflected that his was a life well lived. A man of action and significant achievements, Prince Philip became a naval commander at a young age and provided steadfast counsel to Her Majesty The Queen throughout her reign. When his young wife first took on the role as monarch, the newly titled Duke of Edinburgh supported her, showing tireless dedication to his duty. This exemplary service was recognised by The Queen at the time of their 70th wedding anniversary in 2017, when he was appointed a Knight Grand Cross of the Royal Victorian Order (GCVO). In honour of this remarkable man, The Royal Mint has created a coin to celebrate his life and legacy. The design features a portrait created by Ian Rank-Broadley FRBS that was personally approved by The Duke of Edinburgh in 2008. | 
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