Whatever happened to King Charles’ "beloved" stuffed animal Teddy? Christopher Andersen claims to know the truth.

The bestselling author has written a new book about Queen Elizabeth II's eldest son, "The King: The Life of Charles III." Andersen spoke to numerous palace insiders and those who’ve known the former Prince of Wales or worked with him closely over the years. 

His goal was to further investigate the 74-year-old’s "lonely" childhood, military training and several scandals surrounding his relationships that rocked the House of Windsor.

In the book, Andersen claimed that Charles’ childhood toy traveled with him well into his 40s. And whenever Teddy lost a button or "began to fray," Charles' former nanny, Mabel Anderson, was called upon to bring him back to health. 

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King Charles holding a teddy bear

Author Christopher Andersen claims King Charles III traveled with his childhood teddy bear well into his 40s and still owns the childhood toy, which is named Teddy. (Getty Images)

"He still has Teddy," Andersen told Fox News Digital. "As a matter of fact, Mabel Anderson … was the only person who was allowed to mend this bear for decades and decades. And only recently has she stopped. She’s still alive and still very close to Charles if you can believe it. [And] he travels with this teddy bear."

Mabel Anderson with Prince Charles

Prince Charles, heir to the British throne, riding in his pram pushed by his nanny, Mabel Anderson.  (Getty Images)

A former assistant valet told Andersen the beloved nanny "was the only human being allowed to take needle and thread to Prince Charles’ teddy bear. He was well into his 40s, and every time that teddy bear needed to be repaired, you would think it was his own child having major surgery."

Andersen said Teddy is incredibly symbolic of Charles’ childhood. His mother, then-Princess Elizabeth, was crowned queen in 1953. Four-year-old Charles received a hand-painted invitation to the ceremony. The prince, a shy boy with a domineering father, grew into a sometimes awkward, understated man. Some sources claimed that, as a child, Charles was also bullied by his classmates as his parents immersed themselves into their royal roles.

King Charles as a child looking outside his window

Prince Charles using binoculars to view the coronation scene from a window at Buckingham Palace. (PA Images via Getty Images)

"The teddy bear is symbolic of so much," Andersen explained. "I always go back to this one incident [from his childhood], and I think it speaks volumes. … [His mother had] been away for six months touring the Commonwealth, her first trip abroad. And she gets off the ship, and he rushes up to her, and she kind of shoves him aside. This is caught on newsreel. You can see it. 

"And she greets the adult dignitaries and whatnot. And then, when she finally acknowledges him, she reaches down and shakes his hand. Doesn’t hug or kiss him. And you contrast that with [Princess] Diana in the way that she scooped up [her] boys whenever she was around. [She] hugged them, kissed them, very affectionate. So Diana really injected the family with this kind of humanity that never was there before."

A young Prince Charles looking serious

Sources have said that King Charles was bullied by his classmates while growing up. (Getty Images)

"I interviewed Margaret Rhodes, who was the cousin to the queen and very close [to her]," Andersen shared. "She said the relationship between Charles and his parents was never cozy because the family isn’t set up to be cozy. And I think that was very revealing."

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According to Andersen, Diana once told a journalist friend, "Charles was so lonely as a boy. He’s never gotten over it."

King Charles enjoying a mojito

Christopher Andersen claims that, like his mother and grandmother, King Charles III prefers round ice cubes and will even travel with his own ice tray. (Chris Jackson/Pool/Getty Images)

Andersen said he was delighted to learn that Teddy isn’t the only accessory that is said to join Charles during his travels. Andersen claimed in his book that the king’s valet must carry his hand towels, Kleenex Premium Comfort brand luxury toilet paper and a custom-made white leather cushioned toilet seat. Charles allegedly also uses his own plates and utensils, and a chef accompanies him to prepare separate dishes.

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"We used to joke that he was afraid of being poisoned," a longtime friend claimed to Andersen. "But he really is just accustomed to getting precisely what he wants when he wants it, regardless of how that makes other people feel."

Andersen also says the king prefers a dry martini, and salt must be served in a small silver bowl with his crest, never a shaker. He noted that while Charles himself denied traveling with his own toilet seat in 2018, "several royal protection officers and staff" insisted he does.

King Charles having tea with Camilla

Christopher Andersen claimed King Charles, seen here having tea with his wife, Queen Consort Camilla, travels with his personal chef. (Getty Images)

"He also travels with an ice cube tray that only makes round ice cubes," Andersen claimed. "He insists on round ice cubes because square ones make too much noise. The Queen Mother did the same thing, and the queen did the same thing. … When he shows up at someone’s house for a dinner party, he brings his own chef to make a separate meal for him. He has a very interesting, quirky lifestyle. … [He’s] a very multidimensional character."

Andersen described Charles as "a work in progress."

King Charles looking serious

Prince Charles became king after his mother, Queen Elizabeth II, died Sept. 8 at age 96. (Getty Images)

"I think we all knew who the queen was," he explained. "She knew who she was, but he is still very much a work in progress. He’s much more complicated than people think. He’s much more sensitive than people think. And, at the same time, he’s going to take the bull by the horns. I think he really intends to transform the monarchy, modernize it. 

"He called it ‘slimming it down,’ and that means kicking some people off the royal payroll. So we’ll see how that works. … But in the end, it all comes down to his childhood, which I think is so touching and so heartbreaking. … I think that’s the key to the kind of king he is and will become."

King Charles bored during Queen Elizabeth's coronation

The Queen Mother (left) with her grandson Prince Charles (center) and his aunt Princess Margaret Rose (1930-2002) in the royal box at Westminster Abbey watching the coronation ceremony of Queen Elizabeth II.   (Topical Press Agency/Getty Images)

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A spokesperson for Buckingham Palace didn’t immediately respond to Fox News Digital’s request for comment. However, a spokesperson previously told Fox News Digital "we don’t comment on such books."

The Associated Press contributed to this report.