A 2007 £2 error British coin, struck on a solid planchet was found by a collector. The coin was supposed to be struck as a ringed-bimetallic coin, with an inner disc of copper-nickel and an outer band of nickel-brass. The collector initially thought that the coin was fake. However, the size and weight were the same as other £2 coins and there was no join for a central inner disc.
On most bi-metallic coins, the inner disc is put into the outer band and the two parts are merged when pressure is applied to strike the coins. The collector checked with the Royal Mint Museum in September 2016 to find out how the error originated.
Experts revealed that an unpierced nickel-brass blank had been struck between the two dies for the 2007 technology £2 coin. Only four to five similar coins have been spotted but the £2 error coin is unique. Very few error coins have been discovered in the last 10 years.