King Charles may be smiling beside Prince William in public, but behind palace doors, insiders claim the monarch is growing increasingly frustrated with his heir — and may even find William more irritating right now than Prince Harry.

For years, Charles and William have been carefully presented as the stable center of the royal family, especially as the House of Windsor continues to deal with Prince Harry and Meghan Markle’s public break from royal life. But according to palace sources and royal commentators, a new tension is simmering between the King and the Prince of Wales, and it centers on one of the monarchy’s most sensitive subjects: duty.

Charles, who continues to undergo cancer treatment, has reportedly carried out official engagements on 175 days over the past year. William, meanwhile, has faced renewed scrutiny over what critics describe as a lighter public workload, with his diary appearing noticeably less packed and his family time more carefully emphasized.

That contrast has allegedly not gone unnoticed by the King.

“There is a growing sense that the King feels the weight of the institution resting largely on his shoulders,” a source with knowledge of palace dynamics told RadarOnline.com. “He is acutely conscious that he is still undertaking a substantial number of engagements while dealing with a serious illness, and that contrast has begun to grate behind the scenes.”

The source said Charles does understand William’s desire to be a more present father to Prince George, Princess Charlotte and Prince Louis. But that same image of William as a hands-on modern dad has reportedly stirred up old sensitivities for the King, who has long faced criticism over his own parenting, particularly in the years following his split from Princess Diana.

“Charles genuinely appreciates William’s desire to be a very present, hands-on father,” the insider said. “At the same time, he cannot entirely shake the feeling that this carefully crafted image inevitably invites comparisons with his own past, and that those comparisons do not always fall in his favor.”

The alleged tension comes at a complicated moment for the royal family. Harry recently completed a four-day visit to the United Kingdom, where he attended Invictus Games-related events, took part in charity engagements and met with Charles at Clarence House.

The visit was widely viewed as one of Harry’s smoother public appearances in Britain in years, especially after a long stretch of public criticism, family feuding and damaging headlines.

Royal biographer Tina Brown has suggested that Harry’s recent image reset may be landing better than expected — and that Charles’ irritation may now be aimed less at his younger son and more at William.

“The king is, I am told, currently less irritated with the prodigal Harry than he is with his elder son and heir,” Brown said. “Somehow, William’s parenting dedication always seems couched as a tacit criticism of the king’s own paternal deficiencies.”

Brown also pointed to William’s schedule, noting that after multiple family vacations in recent months, his first week back included only a small number of public outings, including a father-daughter appearance at a Women’s Rugby World Cup pool match and a visit to the Natural History Museum’s new gardens.

By comparison, Brown said, Charles has continued carrying out a heavy schedule despite his ongoing health battle.

That contrast, she argued, could create an uncomfortable question inside the monarchy: how much work should the future king be doing while his father, already on the throne and undergoing cancer treatment, continues to shoulder much of the public burden?

Harry’s latest trip may have made that question even harder for William to avoid.

Brown described Harry’s return as a surprisingly successful “reset,” saying the Duke of Sussex appeared to have rediscovered a basic royal formula: show up, support charitable causes and smile.

“At last, Prince Harry has got it right, which is bad news for the Prince of Wales,” Brown said. “After five years of exuding choler and wrath and spouting therapeutic gibberish, the ginger whinger finally realized that all the royals have to do to win public enthusiasm is zip around the UK and smile.”

Harry also drew attention for contributing £1.1 million of his own money to a Children in Need project, a move Brown said could intensify questions around William’s finances and public role.

The Prince of Wales reportedly receives around £23 million a year through the Duchy of Cornwall, a massive private estate that funds the heir to the throne’s official, charitable and private expenses. Harry’s personal donation, Brown argued, could prompt critics to ask what William is doing with his own substantial resources.

Harry’s team, meanwhile, framed the duke’s return to Britain as a positive and meaningful trip.

A spokesperson said Harry had “loved being back in the UK, catching up with old friends, colleagues and just generally being able to support the incredible work of the causes that mean so much to him.”

During his visit, Harry appeared at a Diana Award event in London, where he spoke to about 40 young changemakers about mental health, activism and social action.

“Getting involved in peaceful social action takes courage and determination,” Harry told the group. “Young people see the issues society faces close up — whether that’s poor mental health or the consequences of inequalities. But you don’t stand still; your empathy and compassion drive you to make change.”

Harry also invoked the legacy of his late mother, Princess Diana, saying she believed strongly in the power of young people to make the world better.

“My mother believed in the power and agency of young people to positively impact the world,” he said. “The Diana Award continues her legacy by putting young people at the heart of everything they do.”

He added: “My message to everyone is don’t stand still, don’t stay silent — make them hear you because you speak for the majority.”

Dr. Tessy Ojo, chief executive of the Diana Award, warned that young people are facing a serious mental health crisis, saying one in five is living with a diagnosable mental health condition and four in ten feel powerless about the future.

“This is why the Diana Award launched the ‘decade of youth wellbeing’ a year ago, prioritising mental health for young people globally,” Ojo said. “When young people are trusted to lead and take action, their wellbeing rises, their resilience grows, and hope is restored. Put simply, action heals minds.”

For Harry, the appearance marked another effort to reconnect his public image with service, charity and his mother’s legacy. For William, however, it may have created a fresh headache.

While the Prince of Wales has long been seen as the monarchy’s reliable future, the latest palace whispers suggest Charles may be growing impatient with how carefully William is shaping that future — especially while the King continues to carry the crown through illness, family drama and a public still watching every move.