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 commemorative £5 Crown-sized coin was issued as part of a six-coin set of similar coins commemorating the Centenary of the First World War; the set itself is the fourth part of a series of sets issued over several years. This coin commemorates the role of Medical Services during the war.
The First World War presented new challenges for the medical services of all the nations engaged in the combat and proved to be a catalyst for great progress in the treatment of patients. Success in the war depended on soldiers being kept fighting fit and an emphasis was put on providing the best medical services. Medical support work and nursing were some of the most significant ways in which women could directly contribute to the war effort and they volunteered in their thousands. Many wartime developments in medical treatment went on to benefit public healthcare once the war was over, including blood banks, splints, and plastic surgery.
The coin was designed by David Rowlands:
“As always, my interest is in the human element of conflict. The perspective of the design is from the soldiers’ eye level. While we might imagine that soldiers on the front line saw the enemy, most rarely did, as they were eight feet down in the trenches. My design shows a Red Cross flag flying in the background, an international symbol to dissuade the enemy from attacking while the wounded were treated. I wanted to convey the human sacrifice and selfless dedication of the medical services, tending the wounded among the increasingly destructive shellfire and bombing.”
The edge lettering "IN ARDUIS FIDELIS" translates to "Faithful in Adversity" and is taken from the badge of the Royal Army Medical Corps.
The coin was issued in Proof FDC, in sterling silver and in a gold, both in sets only and not issued individually. | 
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