The test, known as the Trial of the Pyx, was designed to prevent counterfeiting by inspecting and weighing a sampling of thousands of coins from The Royal Mint to ensure they met the strictest ...

Only 400 1oz gold versions of the coin have been struck, the 1kg silver coin is limited to just 64 coins. The Royal Mint says the release coincides with what would have been Lennon's 85th birthday.