The 20p piece is a rare “mule” coin dating from 2008, and fetched £90 at auction. The coin was minted without a date due to an error and quickly became a sought-after collector’s items.

Brits have been urged to check their change for a seemingly ordinary coin that could be worth 300 times its face value. According to an expert a number of 20p pieces could fetch up to £60 each ...