At the time of decimalisation in 1971, the United Kingdom Crown coin (equal to 5 shillings) was redenominated as a 25p coin and pieces struck prior to 1990 - all the way back to 1818 - continue to be legal tender for that amount. The old denomination had been a regular circulating coin in the 19th century, but in the 20th century it became more of a commemorative denomination.
The Royal Mint continued issuing commemorative coins in the same format - using the traditional coin dimensions, but in copper-nickel. These were initially also denominated as 25 pence but the "Crown" was changed in 1990 to a commemorative £5 (five pound) coin, having the same dimensions and weight but with a face value twenty times as great.
The denomination is used to mark special occasions, usually royal in theme, rather than for use in general circulation. Although not circulating, these coins are legal tender.
This £5 Crown-sized commemorative coin is part of a series of coins by the Royal Mint dedicated to Peter Rabbit, the main character in the famous children's books by British author Beatrix Potter.
Earlier coins had been in the 50 denomination, but in 2021 the Royal Mint released for the first time a £5 coin and two one-ounce coins in precious metals - silver and gold.
The Mint says:
"Mischievous Peter Rabbit was the first Beatrix Potter character to be celebrated by The Royal Mint in partnership with Penguin Random House UK, and the blue-jacketed bunny has since gone on to star on a series of 50p coins. Each year, we’ve brought more of Peter Rabbit’s adventures to life in a series of beautiful designs, carefully selecting iconic images that recall his most memorable moments. Whether he’s squeezing under a garden gate in search of mischief, or munching on radishes after another scrape with Mr. McGregor, each release featuring Peter Rabbit has been eagerly anticipated - a testament to his timeless charm and the skill involved in the meticulous recreations of the hand-painted illustrations which brought Beatrix Potter’s iconic books to life.
2021 is an extra special year for Peter and The Royal Mint as Britain’s favourite bunny hops onto a new coin, appearing on a UK one ounce and £5 coin for the very first time. To mark the switch to a new denomination, Ffion Gwillim and the coin production team were determined to do something extra special." | 
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