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 celebrates the life and legacy of one of the world’s most pioneering and influential leaders, Mahatma Gandhi.
The mint says:
"Born on 2 October 1869 in Porbandar, India, Mohandas Karamchand Gandhi was a lawyer, politician, philosopher and social activist. Driven by his deep spiritual convictions, he is revered for his tireless fight for human rights and for leading the movement for Indian independence against Britain. Gandhi inspired millions with his insistence on peace and truth and his activism focused on Satyagraha or non-violent resistance. During his lifetime, his followers called him ‘Mahatma’, which is Sanskrit for ‘great soul’, and he is still widely recognised by that name today.
The Royal Mint is proud to honour one of the greatest figures of the twentieth century with a brand-new design. Created by the designer Heena Glover, the Mahatma Gandhi 2021 UK Coin features a lotus, the national flower of India, which symbolises Gandhi’s gentleness, strength and his ability to thrive when faced with adversity. The coin’s reverse also features one of Gandhi’s most profound quotes – ‘My life is my message’.
The Mahatma Gandhi 2021 UK Coin is the perfect keepsake to commemorate an icon who changed the world and whose vision of hope, peace and tolerance still resonates more than seven decades after his death." | 
Search for United Kingdom: Five Pounds 2021 Mahatma Gandhi on eBay 
