The Olympic Football coin, which explains the offside rule and has a mintage of 1,125,500, is worth £20.
Triathlon, with a mintage of 1,163,500, is worth £16. Judo, with a mintage of 1,161,500, would go for £18.
The wrestling variation, with a mintage of 1,129,500, is reportedly worth £14.50.
The Royal Mint provided a short history of how the 50p coin came to be: “In October 1969, 50p coins joined the 5p (shilling) and 10p (florin) coins in circulation, leaving only the three copper coins – to be introduced on February 15, 1971 – to complete the new series of decimal coins.