The 20p piece is a rare “mule” coin dating from 2008.
The coin was minted without a date due to an error and quickly became a sought-after collector’s items.
Prior to November of that year, the date on 20p coins would be found on the tail side. However, the Royal Mint switched it so that the date would now be next to the Queen’s head.
A mistake in 2008 led to the old format being used on the Queen’s side and the new format being used on tails side. As a result, the first batch of British coins with no date on them was released into circulation for the first time in more than 300 years.
Around 250,000 20p coins minted in November 2008 are believed to have entered circulation with no date.
The description on the coin, which sold on Thursday, said: “This rare 20p Mule coin is a must-have for any serious collector.
“The coin features an undated 20p denomination and is in high grade, making it a valuable addition to any collection. The coin is from the United Kingdom and is believed to have originated in England.”
After attracting seven bids, the 20p coin sold for £50.
Rarest Royal Mint coins in circulation the UK
The rarest is the Kew’s Garden 50p, which was designed to mark the 250th anniversary of the gardens in 2009. Only 210,000 coins were ever minted with this design.
The Kew Gardens 50p sells for £156.25 on average, but one seller received over £700 for one when they sold it on eBay.
The other rarest coins stem predominantly from the 2011 Olympics, with the wrestling, football and judo coins among the most valuable. Only 1.1million of each of these coins were produced.
Flopsy bunny and Peter Rabbit designs which were produced in 2018 are also highly valuable.
These coins – 1.4 million of which were minted – depict the characters from Beatrix Potter’s novels and celebrate the life of the English writer and these sell for around £5.
In 2019, 500 million coins were produced, with three new 50p designs.
These included one of Arthur Conan Doyle’s Sherlock Holmes, Paddington Bear at St Paul’s Cathedral and the Tower of London.
