CNN
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A childhood letter written by King Charles to his “granny” has been discovered by a couple living in Warwickshire, England, as they cleared out their attic during the Christmas break.

“Dear Granny, I am sorry that you are ill. I hope you will be better soon,” the letter reads on one side, carefully written on lined Buckingham Palace notepaper and dated March 15, 1955, when the King was six years old.

“Lots of love from Charles,” it says on the other side, alongside colorful kisses and doodled circles.

It was discovered inside an envelope addressed from Queen Elizabeth II to the Queen Mother, providing a “three generation run,” Charles Hanson, owner of Hansons Auctioneers and who is responsible for the sale of the letter, told CNN Thursday.

Finding the letter, which Hanson estimates could fetch as much as £10,000 ($12,000) at auction, left the couple “gobsmacked” as they sifted through their loft.

“It had belonged to my late grandad Roland Stockdale,” the seller, a 49-year-old farm manager who has not been named, said in a statement.

“My wife said ‘wow, look at that!’ We were pretty gobsmacked but we weren’t sure whether anyone would be interested in it.”

Stockdale worked for the Metropolitan Police where he was part of the Queen’s personal protection force during the 1950s after he had left Carlisle, northern England, and his previous job as a farm worker, the seller added.

Stockdale’s folder containing the letter had “been gathering dust” in various attics for “30 to 40 years” as it was passed around family members following his death.

“I have absolutely no idea how he came to have the letter written by King Charles when he was a boy,” the seller said. “It’s one of many things he kept.”

Citing postcards and birthday greetings that Stockdale received from the Queen and Queen Mother, Hanson hypothesized that “these keepsakes were gifted to the officer” since he “was clearly so highly regarded.”

The couple found other royal memorabilia in the folder, including an invitation to a dance at Balmoral Castle, a note signed by the Queen Mother, gift tags signed by Queen Elizabeth II and Prince Philip, as well as a copy of the Queen’s 1956 Christmas broadcast.

The items will go on sale March 7.