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EXCLUSIVE: Prince William was allegedly disappointed that Prince Harry and Meghan Markle featured Princess Diana’s image on the homepage of their non-profit organization Archewell.

In late 2020, the Duke of Sussex described himself as his "mother’s son" on the website and included a sweet photo of the young prince perched on his mother’s shoulders. Another photo featured the expecting Duchess of Sussex as a girl with her mother, Doria Ragland.

In "A Letter for 2021," the couple wrote: "I am my mother’s son. And I am our son’s mother. Together we bring you Archewell."

"We believe in the best of humanity," the statement continued. "Because we have seen the best of humanity. We have experienced compassion and kindness. From our mothers and strangers alike."

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Princess Diana carries Prince Henry (Harry) on her shoulders at Highgrove. (Tim Graham Photo Library via Getty Images)

Nick Bullen, co-founder and editor-in-chief of True Royalty TV, told Fox News the Duke of Cambridge was allegedly displeased that his younger brother featured their late mother’s image to promote Archewell.

The award-winning documentary filmmaker has been making programs about the British royal family for nearly 20 years and has worked closely with Prince Charles for eight.

"I think that both William and Harry feel they are carrying on the unfinished work of their mother, but I’m told that William was very unhappy that Harry and Meghan used Diana’s imagery to promote their work when Harry claimed to be ‘his mother’s son’ on their website," he explained.

"Harry knows the power that the Diana legacy carries in America and he’s definitely utilizing that, but it’s something he needs to be careful about," said Bullen. "He doesn’t own the legacy; he shares it with his brother."

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In their statement, the couple announced that the foundation, which will "unleash the power of compassion to drive systemic cultural change," is partnering with five different organizations. 

Now, in an upcoming sit-down with Oprah Winfrey, Harry, 36, invoked the memory of Diana once more. He noted how the Princess of Wales had to find her way alone after she and Charles divorced.

"I’m just really relieved and happy to be sitting here talking to you with my wife by my side because I can’t begin to imagine what it must have been like for her going through this process by herself all those years ago," said Harry, adding, "because it’s been unbelievably tough for the two of us."

"But at least we have each other," said Harry in a clip from the interview special, which also showed Diana holding toddler Harry as he made the comments.

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Princess Diana passed away in 1997 from injuries she sustained in a Paris car crash. The Princess of Wales was 36. (AP Photo/Jim Bourdier)

Diana passed away in 1997 at age 36 of injuries suffered in a car crash.

On Feb. 15, CBS announced Harry and Markle, 39, will be interviewed by Winfrey, 67.

The sit-down, titled "Oprah With Meghan and Harry: A CBS Primetime Special, will air on Sunday, March 7. The special will also be the couple’s first sit-down since their engagement.

"Oprah Winfrey as she sits down with Prince Harry and Meghan, The Duke and Duchess of Sussex, for an intimate conversation for an exclusive primetime special," the press release stated.

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It was previously announced that Prince Harry will be partnering with Oprah Winfrey to create a documentary series on mental health for Apple's streaming service. (Getty)

"Winfrey will speak with Meghan, The Duchess of Sussex, in a wide-ranging interview, covering everything from stepping into life as a Royal, marriage, motherhood, philanthropic work to how she is handling life under intense public pressure," it continued.

"Later, the two are joined by Prince Harry as they speak about their move to the United States and their future hopes and dreams for their expanding family."

The announcement came just a day after the royal couple revealed on Valentine's Day that they are expecting their second child. In 1984, Diana had also announced on Valentine's Day she was expecting her second child - Harry.

"They are speaking now because they are trying to build Brand Sussex for a US audience, as was seen in the James Corden interview and now in this interview with Oprah," said Bullen.

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Royal insiders have long alleged Prince William (right) and Prince Harry (left) have faced obstacles in their relationship. (Getty)

On March 7, Queen Elizabeth II will also speak in a TV address for Commonwealth Day, which will air on BBC One. Last year’s Commonwealth Service at Westminster Abbey marked the final royal appearance made by the Duke and Duchess of Sussex. This year’s plans were scrapped due to the ongoing coronavirus pandemic.

Other senior members of the royal family, including William, Charles, as well as Kate Middleton, among others, are expected to participate.

Commonwealth Day is on Monday, March 8.

Still, Bullen said he doesn’t expect the palace - or any of its senior members - to publicly speak out about the Winfrey interview.

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James Corden and Prince Harry have been friends for years. The British TV host even attended the royal wedding of the Duke and Duchess of Sussex. (Getty)

"They won’t respond and won’t give it air time because the mantra of the Windsor family is: ‘never complain, never explain,’" he said.

Winfrey attended the couple’s royal wedding back in May 2018. The couple also lives in Montecito, Calif., where they are neighbors of the media mogul.

While the interview has already been taped, Bullen wished it would address the allegations made by The Times. On Tuesday, the U.K.-based outlet reported that a former aide had made a bullying allegation against the Duchess of Sussex during her time as a working royal at Kensington Palace. The adviser alleged that Markle drove out two personal assistants and left staff feeling "humiliated."

The official complaint was made by Jason Knauf, who originally served as the couple’s communications secretary. He now works for William.

The palace said it was "clearly very concerned" about the allegations. A spokesperson for Markle said she was "saddened by this latest attack on her character, particularly as someone who has been the target of bullying herself and is deeply committed to supporting those who have experienced pain and trauma."

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A spokesperson for Meghan Markle said the Duchess of Sussex is 'saddened' by allegations of bullying. (AP)

"I would love for them to address what the truth is behind the bullying allegations made against Meghan," said Bullen. "Why is she saying that the palace is trying to discredit her? Meghan positions herself as a great advocate of compassion and yet there are people saying that she drove them to tears. It would be good to try and understand those two narratives."

Harry and Meghan stepped away from full-time royal life in March 2020, unhappy at media scrutiny and the strictures of their roles. They cited what they described as the intrusions and racist attitudes of the British media toward the duchess, who is African American.

It was agreed the situation would be reviewed after a year. On Feb. 19, Buckingham Palace confirmed that the couple will not be returning to royal duties and Harry will give up his honorary military titles — a decision that makes formal, and final, the couple’s split from the royal family.

The pair verified "they will not be returning as working members of the Royal Family. "

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Meghan Markle and Prince Harry currently reside in California with their son Archie. (AP)

A spokesperson for the couple hit back at suggestions that Meghan and Harry were not devoted to duty.

"As evidenced by their work over the past year, the Duke and Duchess of Sussex remain committed to their duty and service to the U.K. and around the world, and have offered their continued support to the organizations they have represented regardless of official role," the spokesperson said in a statement.

The Associated Press contributed to this report.