Like many other mints, the Royal Mint issues bullion coins in precious metals, having much higher intrinsic value than their face value. The one-fortieth ounce (1/40 oz) gold coins are denominated as Fifty Pence (50p) and have been issued since 2014.
These tiny coins are legal tender but are not intended for circulation. They are targeted at 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 commemorative coin is dedicated to the Buckingham Palace in London.
The mint says about it:
Since 1837, Buckingham Palace has served as the official London residence of the British monarch. Today, it is the administrative headquarters of the British monarchy, as well as acting as a hub for national and royal celebrations.
King George III bought Buckingham House, as it was then known, in 1761 for his wife Queen Charlotte. Regarded as a comfortable family home close to St James’s Palace, Buckingham House was the location for the birth of all but one of George III’s and Queen Charlotte’s 15 children. The building underwent various reconstructions over the ensuing decades as it was transformed from a house into a palace, and Queen Victoria became the first British monarch to rule from Buckingham Palace when she took up residence there in July 1837.
Today, the Palace is very much a working building, playing host to royal events attended by more than 50,000 guests each year, including Heads of State from around the world. The Palace boasts 775 rooms, including 19 State Rooms that are used by the Royal Family for official entertaining and are open to visitors every summer. | 
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