Following the news of King Charles' cancer diagnosis, royal family members are "very thin on the ground," according to royal expert Neil Sean.

Sean — who has over 20 years of experience covering the royal family — was a guest on "The Story with Martha MacCallum" on Monday where he pointed out that the royal family has been very tied up these past several weeks.

"This is a difficult bit, Martha, because obviously, the Princess of Wales, Catherine, is incapacitated back recovering herself," Sean said of Kate Middleton's recent abdominal surgery. "And then, of course, you have Prince William who is also on daddy duties." 

King Charles looking somber

King Charles' cancer diagnosis leaves royals "very thin on the ground," royal expert Neil Sean said. (Getty Images)

He continued, "So now, we're going to have to see the Duke and Duchess of Edinburgh and, of course, the Princess Royal — but it does leave the royals very thin on the ground."

KING CHARLES DIAGNOSED WITH CANCER, BUCKINGHAM PALACE SAYS 

William, Prince Edward, the Duke of Edinburgh, Anne, the Princess Royal and Queen Camilla all make up the four counselors of state in place if the king becomes incapacitated. 

Sean said this time for Camilla is "difficult" as she will likely need to step away from her royal duties to aid Charles, which she "will want to do." However, Charles "will want her out and about."

WATCH: King Charles wants to be transparent: Neil Sean

On Monday, Buckingham Palace released a statement, sharing that the king was diagnosed with a form of cancer and is undergoing treatment. 

"During The King’s recent hospital procedure for benign prostate enlargement, a separate issue of concern was noted," Buckingham Palace said in a statement. "Subsequent diagnostic tests have identified a form of cancer."

KING CHARLES RELEASED FROM HOSPITAL FOLLOWING PROSTATE TREATMENT 

A source confirmed to Fox News Digital that Prince Harry and King Charles spoke about his diagnosis before His Majesty went public with his health concerns.

Kate Middleton smiles wearing a blue suit

Kate Middleton was hospitalized last month for a planned abdominal surgery. (Samir Hussein)

"The Duke did speak with his father about his diagnosis," a source confirmed to Fox News Digital. In addition, Harry "will be traveling to UK to see His Majesty" in the coming days.

Sean advised Harry to "leave" his wife, Meghan Markle, "at home" when he returns to the United Kingdom.

Prince Harry and Meghan Markle smile as senior royals

Royal expert Neil Sean advised Prince Harry to "leave" Meghan Markle at home when he returns to the U.K. (Chris Jackson)

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Sean also says it's going to be "tricky" for Harry once he returns to the United Kingdom because "he's very much disliked." 

"What we have to remember is that he is a family member, naturally concerned about his father," Sean added.

Prince Harry

Sean said it will be "tricky" for Prince Harry to return to the United Kingdom because he's "very much disliked," but to remember "that he is a family member, naturally concerned about his father." (Wiktor Szymanowicz/Anadolu Agency)

MacCallum mentioned that Buckingham Palace previously kept the late Queen Elizabeth II's cancer diagnosis private.

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Sean believes Buckingham Palace decided to share Charles' diagnosis early on because "we live in a different world, it's a digital world." 

"Truly, the situation is this," Sean continued. "His majesty the King wants to nip this in the bud and be transparent and say ‘this is where I’m at now,' so people don't speculate and make grave misdemeanors regarding it."

King Charles III and Queen Camilla

King Charles III and Queen Camilla attended the Sunday service at St. Mary Magdalene church on the Sandringham estate on Feb. 4. (Max Mumby/Indigo)

Charles was seen at St. Mary Magdalene Church near Sandringham on Sunday, which Sean believes was "a very big message" from the King.

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"It's very clever in their communications of what they're doing," Sean said of Buckingham Palace. "Seriously though, we just wish him the best. It's very upsetting news actually over here in the United Kingdom and, of course, to the rest of the world – the Commonwealth."