"This issue impacted less than 250,000 coins out of the 136 million 20p pieces minted in 2008 and was a result of pairing the old obverse, or heads side, with the new reverse, or tails side design ...
From checking the back of the sofa to asking for extra change at the till, you could make a profit if you have this 20p coin which features an error. The rare undated ...