Like many other mints, the Royal Mint issues bullion coins in precious metals, having much higher intrinsic value than their face value. The five ounces (5 oz) gold coins are denominated as either ten pounds (£10) or five hundred pounds (£500).
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 smaller denominations with the same reverse designs.
This commemorative 5oz gold coin is part of a series celebrating the 40th birthday of HRH The Duke of Cambridge (Prince William).
The Mint says about it:
Growing up during the eighties and nineties as a popular prince, His Royal Highness The Duke of Cambridge has evolved into his senior royal role with seamless confidence. In addition to his ceremonial duties, which include supporting his grandmother, Her Majesty The Queen, His Royal Highness works tirelessly to make an impact on progressive causes that remain close to his heart - whether it’s tackling the issue of climate change or the stigma attached to mental health issues. As a devoted husband to Her Royal Highness The Duchess of Cambridge and a loving father to their three young children, this year The Duke of Cambridge celebrates his milestone 40th birthday. | 
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