Prince Harry sparked criticism for speculating about the King’s health after saying he didn’t “know how much longer” he has left to live.
Charles, 76, who is having cancer treatment, is believed to be “frustrated and upset” with the Duke of Sussex over his handling of their ongoing security dispute and his public criticism of the Royal Family.
In an interview with BBC News after losing a Appeal Court legal challenge, Harry said he wants a “reconciliation” but claimed: “Life is precious. I don’t know how much longer my father has, he won't speak to me because of this security stuff.”
Ailsa Anderson, a former press secretary to the late Queen, told Sky News that Buckingham Palace will be “raising their eyes heavenwards” in reaction to his latest broadside.
She told presenter Sophy Ridge: “Prince Harry is saying ‘I don’t know how long my father has’ – that’s going to cause real concern and more speculation in the media and the wider public about what his diagnosis is, which is incredibly unhelpful going forward.
“What you don’t want to do is have your private life played out in the media. So if you truly want reconciliation, you’ll do it in private, not in a BBC News interview.”
Royal commentator Joe Little added a “dignified silence” would have been a wiser move for the duke but he has given his family “nothing” to suggest he can be trusted with their private information.

Majesty Magazine’s managing editor described comments about the health of Charles “quite alarming”, saying: “Is Harry suggesting that the King isn’t as well as we are led to believe?”
Ken Wharfe, who was a royal protection officer to royals including Harry, William and their mother, Diana, Princess of Wales, noted if he has greater knowledge than most people about Charles’s health, the 40-year-old “may have a good reason to worry about how long his father has to live”.
It would mean “there’s even a greater wish upon his part, perhaps, to see his father and to reconcile his differences”, Mr Wharfe said, adding: “The fact that his father has cancer must be a very worrying aspect for him.
“I think this situation he currently finds himself in must be incredibly lonely.
“I’m sure he is ultimately concerned about his father’s health.”
A royal insider told The Sun that while Charles believed it would have been “constitutionally improper” to intervene in Harry’s legal case, he has been personally hurt by his son’s actions.
“What has frustrated and upset him on a more personal level is the Duke’s failure to respect this principle,” the insider said. “And for his supporters to suggest that somehow his father doesn’t care about his family, or should step in.
“He’s been particularly concerned that it has taken considerable resources and cost for the Government to defend their position.”
The Duke of Sussex told the broadcaster he “can’t see a world” in which he would bring his wife and children back to Britain having stepped back from duties to live in California.
Despite the criticism, the Palace has remained firm in its stance.
A spokesman for Buckingham Palace said of the long-running security battle: “All of these issues have been examined repeatedly and meticulously by the courts, with the same conclusion reached on each occasion.”
In his interview, Harry also described the court ruling as a “good old-fashioned establishment stitch-up”.

But Mr Wharfe told the PA news agency: “On the security issue, I think he has really played the wrong card.
“I don’t see how he can expect to get full protection when he arrived back in the UK, when he is no longer a member working the royal family, when he knows that the actual security package comes at the expense of the British taxpayer.
“The government and the police are quite together on this.
“They are saying, ‘well, we understand that, but we can’t suddenly just push on buttons to give you the all-singing-and-dancing protection that you had when you were in United Kingdom,’ the same that his mother had, his brother enjoys, and now it is, of course, his father and Queen Camilla.
“What the government has given and the police is a protection of sorts to guarantee his safety, which will be based on risk assessment that, quite frankly, is about the best he can expect.
“The High Court has seen that. The appeal court has seen it. The government has seen it. The police have seen it – so where’s the problem?”