The coin struck by The Royal Mint and dated 1990 along with 88,097,499 other 20 pence coins, was found in a bank bag of 20p coins back in 1994, it has been stored untouched in a jewellery box for the last 24 years. This explains the excellent condition of the circulation 20p coin, which is now 28 years old.
This coin may have remained hidden away, but for an article in The Sun Online about a bronze error coin that could be worth £1,350.
A standard 20p coin has 7 sides and is slightly rounded where each of the sides join.
The error coin has 3 sides that match the 20p shape, with the remainder of the coin looking like a circle. This would be expected when a 20p die was struck onto a slightly undersized round blank that is dropped into a 20p shaped collar. The force of the strike forms the full shape of the coin when a normal sized blank is struck.
The 1990 coin which shows the older Heraldic English rose, royally crowned design (1982 to 2008) by William Gardner and the third portrait of the queen by Raphael Maklouf on the obverse.
A letter from Chris Barker, Assistant Curator at The Royal Mint Museum.
The owner of the coin, Steve, contacted Change Checker with a photo of the coin and then contacted The Royal Mint Museum who asked for the coin to sent to them for examination. On the 30th March, this letter confirming the coin to be a genuine Royal Mint error was received.
Examination by X-ray fluorescence spectrometry has confirmed that this is an error in production, whereby a bronze blank, probably originally intended for one of the many overseas coinages produced at the Mint, appears to have been struck between 20p dies.
Steve then spoke to Kieran Clarke from Check Your UK Change who had written an excellent article about circulation coins, which inludes error coins such as the undated 20p.
Kieran mentioned Coin Hunter and we received an email from Steve on the 4th April: I have a bronze 20p coin which has been verified by the Royal Mint please see attached images. Any ideas of value.
A similar coin dated 1987 came to light in November 2017, it had been aquired by 288 Group Ltd in the name of their Change Checker brand from a private collecter, David Crosier.
This coin was placed in a presentation box along with a brilliant uncircullated 1p and 20p coin from the same year. It was then offered as a prize to registered members of Change Checker, with a draw being made on 11th December 2017. No winner information has been released.
There have been a few claims made by other collectors suggesting they have or had similar coins, but after a great deal of investigation, only 2 coins have been proven to exist, with 2 more that although not yet seen, likely to be the real thing.
There is no way to know how many genuine error coins like this made it into circulation, there will likely be more found, but expect very few ever to come up for sale. The coin could be compared with the silver 2p coin errors which are valued at £1,350 based on the price of the most recent coin to sell.