King Charles’ cancer diagnosis could force his sons into an uneasy truce — but it hasn’t happened yet

Prince Harry has still not spoken to Prince William on the heels of their father King Charles’ cancer diagnosis — but the shocking news could force the estranged siblings into an uneasy truce, sources say.

The two were brought up by their mother, Princess Diana, to be a double act, with Harry meant to be William’s trusted advisor once the latter eventually becomes king.

However, they have not spoken for about a year, Page Six is told. Now, as their father faces a health crisis, one well-placed palace source said: “Is this the point where Harry gets to swoop in and be magnanimous and reach out to William?”

Harry, the Duke of Sussex — fifth in line to the throne — was due to leave California Monday to be reunited with his father, who started cancer treatment the same day.

He planned to fly solo to England, as his wife, Meghan Markle, and their children, Prince Archie, 4, and Princess Lilibet, 2, stayed home in Montecito.

Charles, 75, called both his sons to personally break the news of his illness.

King Charles III poses with his sons William and Harry during a skiing vacation in Switzerland, in March 2005. The boys were raised to be a double act, with Harry meant to be William’s trusted advisor once the latter eventually becomes king. Getty Images

Buckingham Palace released a statement Monday, revealing cancer had been found while the monarch was being treated for a benign prostate enlargement. While the palace has not revealed the type of cancer, it is not prostate cancer.

Charles — who also called his siblings, Princess Anne, Prince Andrew and Prince Edward, to inform them of his diagnosis — is being treated as an outpatient in London, and was resting at Clarence House Monday night. He is joined by his wife, Queen Camilla, who will keep her full diary of engagements as well as supporting her husband.

The monarch’s diagnosis, just 15 months into his reign, immediately raised several questions. Among them: Will William have to, at some point, assume the role of Prince Regent? That would allow him to assume all of Charles’ duties — and power — if the king were incapacitated.

Charles raised his sons as a single father after Princess Diana’s death in 1997. But Harry has accused the king of being cold. Tim Graham Photo Library via Getty Images

A Kensington Palace source told us that it was “likely” that William would step in for his father on some engagements.

Writer Hugo Vickers, a friend of the royal family whose books include “Coronation,” told Page Six: “Charles will never abdicate. He’s an anointed king and he’s promised to serve to the end — and I don’t think he would want to [abdicate].”

However, Vickers pointed out that the eldest son of George III was named Prince Regent when his father was deemed mentally unstable to rule in 1811.

Harry, Charles and William were all smiles as they celebrated Harry’s 20th birthday in 2004. But the brothers are now not speaking. ASSOCIATED PRESS

“William could become Prince Regent if Charles could not fulfil his duties, but Charles would remain king in name,” Vickers said.

Another well-placed royal insider told Page Six: “Queen Elizabeth reigned until 96, so I would imagine that William thought he had potentially 20 years to be the Prince of Wales.”

The situation comes at a stressful time for William, 41, as his wife, Kate, is recovering from serious abdominal surgery that will keep her out of public life until after Easter.

William and Harry joined their father on his wedding day to Queen Camilla in April 2005. Buckingham Palace has said that the queen is continuing her schedule as usual in the wake of the king’s diagnosis. Getty Images

William will be back in the public eye when he conducts an investiture Wednesday at Windsor Castle, followed by a gala fundraising event for the London Air Ambulance in the evening.

Meanwhile, he has not spoken to Harry in many months. William was said to be furious over Harry’s bombshell memoir “Spare,” published in January 2023, and accusations that the future king had assaulted his brother during a fight over the treatment of Markle.

There were also claims at the end of last year, in Omid Scobie’s book, “Endgame,” that Charles and Kate were the “racist royals” who had asked about the skin color of Harry and Markle’s mixed-race children — something that threw yet another wrench into William and Harry’s relationship.

William and Harry fell out, in part, over tensions surrounding the younger prince’s wife, Meghan Markle. REUTERS

It is not known where Harry, who has also had a fraught relationship with the man he calls “Pa,” will stay while in the UK

Harry, 39, no longer has a home in the UK after being made to give up Frogmore Cottage, which sits on the Windsor estate.

Sources said that Harry may stay at Buckingham Palace nearby.  He is meant to be launching the next Invictus Games in Canada later this month alongside his wife, but it’s not known whether that trip will be canceled.

Harry’s relationship with his father has been on a knife’s edge since he quit life as a senior working royal.

Charles’ Coronation Day was May 6, 2023. Experts do not expect him to abdicate the throne. BACKGRID

He told Oprah Winfrey in 2020 that Charles stopped taking his calls when he was trying to discuss stepping down as a working royal.

“My father and my brother, they are trapped. They don’t get to leave. And I have huge compassion for that,” Harry told Winfrey.

He also wrote in his book that Charles did not hug him when breaking the news of Diana’s death, and that he believed the king was “never made” for single parenthood, but “To be fair, he tried.'”

William has been hands-on in caring for his wife, Princess Catherine, after her own recent health woes. The two share sons Prince George and Prince Louis, as well as daughter Princess Charlotte. AP

Harry also attacked Camilla, calling her dangerous and keen to rehabilitate her own image.

Following the Duke of Edinburgh’s funeral in April 2021, Charles pleaded with his sons during a tense meeting, “Please, boys. Don’t make my final years a misery,” according to Harry.

Asked what this fresh news means for Charles and his two sons, Vickers replied, “It’s a good thing that Harry is coming over — but the chances of Harry and William becoming friendly again are very slim, to be honest.”