In 2017, the Nickel Brass, round type of one pound coins were discontinued in the United Kingdom and the denomination was changed to a 12-sided bimetallic coin known as the "Nations of the Crown £1" due to its reverse designs which represents the floral emblems of the four constituent nations - England, Scotland, Wales and Northern Ireland.
The new coins entered circulation in 2017, with the bimetallic coins being prepared earlier and dated 2016.
In March 2017, the Royal Mint released a special limited issue set with two coins (both dated 2016): a specially struck "Last Round Pound" (not issued for circulation), and a version of the new 12-sided coin with a special "crosslet" privy mark on the obverse.
Later, this set was issued in 22 carat gold; the 12-sided coin in it is dated 2017 and does not have the privy mark. | 
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