The Edward VIII Sovereign gold coin, as shown on the Royal Mint Instagram account today.

A Sovereign coin depicting Edward VIII, uncle of Her Majesty Queen Elizabeth II, has been sold to a private buyer in the UK for a record £1 million for a coin.

The 22 carat coin was discovered by the Royal Mint’s verification team, who found it to be owned by an American collector who was looking to sell the coin on.

The Sovereign coin bears the portrait of the brief King Edward and was created as a ‘trial coin’ in 1936, ahead of mass production due to begin in January 1937. The coin never made it to widespread release though, due to Edward’s abdication from the throne in order to marry Wallis Simpson. Specimens were held in secret in a safe with the then Master of the Mint, and not discovered until his retirement in the 1970s.

Speaking to the BBC anonymously, the new owner described the purchase as a “once in a lifetime opportunity” and said: “I'm aware that (£1m) is a lot of money for a coin, but if I did not secure it now, I'd not get the chance again.”

Only six of the coins are currently in the public realm. Four of them are in museums or similar institutions, with one actually available for public viewing at the Royal Mint Experience. The other two are held by private investors, including the new British buyer of this Sovereign.

Aside from its incredibly low mintage, the Edward VIII Sovereign is unusual because the King broke tradition for the portrait. Typically, monarchs alternate which way they look. Edward’s father looked left, so Edward should have looked right. He didn’t, on the basis that he preferred his left side. To brush over the mistake, his brother George VI kept a left profile, and daughter Elizabeth II currently faces to the right.

Speaking to reporters this morning, Matt Curtis from the Royal Mint said: “The Edward VIII sovereign is part of numismatic legend, belonging to a series of coins that were never meant to exist and were hidden from the public for decades.

“This sovereign is significant not only because of its rarity but because it sits at the heart of an international story and has been treasured by collectors in both the UK and US.”

Following Edward VIII’s abdication, younger brother George VI ascended to the throne. The film ‘The King’s Speech’ was made about George’s life and his difficulties with shyness and a stammer in his speech, but despite an uneasy start to his reign, George grew steadily more popular during wartime until his death in 1952.