With King Charles out of public duty, the pressure for royals to step up mounts

• On Monday, Buckingham Palace announced King Charles was diagnosed with cancer. 
• The monarch will not be participating in "public-facing duties" while he undergoes treatment.
• Other senior royals will have to step up in the meantime, but the monarchy is smaller than ever.

The announcement Monday that King Charles III has cancer has shone a light on just how fragile the British monarchy is.

Buckingham Palace did not specify what kind of cancer the king has, but it said in a statement shared with Business Insider that he started "a schedule of regular treatments" on Monday. The palace's statement also said the king was diagnosed after medical staff discovered a "separate issue of concern" during a procedure for an enlarged prostate.

While he undergoes treatment, King Charles, 75, will "postpone public-facing duties" while continuing to work on his usual State business from home, according to the statement.

With the king out of commission for public engagements, it will fall to the rest of the royal family to step more into the public eye while he heals. But the list of working royals is growing smaller and older. Even with his son and heir, William, waiting in the wings, it'll be difficult for the family to fill the king's shoes.

The king has fewer senior royals to support him than monarchs of years past

According to the royal family's website, there are 10 working senior royals besides King Charles who can take on in-person engagements for the monarch while he undergoes treatment.

But as royal commentator Kristen Meinzer told BI, the king's team of working royals is smaller than he may have anticipated, though he has yet to enact the plan The Times of London first reported on in 2019 to officially "slim down" the monarchy.

"The problem is it's so slim now because of other extenuating circumstances," Meinzer said, pointing to Prince Harry, Prince Andrew, and most recently, Kate Middleton.

Prince Harry, 39, and his wife Meghan Markle, 42, stepped back as senior royals in 2020, and they have been largely estranged from the royal family, particularly since Harry released his memoir "Spare" in January 2023. Still, Harry plans to visit his father later this week, a representative for the Duke of Sussex told BI.

Likewise, Prince Andrew, 63, hasn't worked for the royal family for years. He resigned from his royal duties in 2019 after documents from Virginia Giuffre's 2015 defamation case against Jeffrey Epstein and Ghislaine Maxwell were unsealed. In the documents, Giuffre alleged that Epstein forced her to have sex with Andrew when she was 17. Andrew was later stripped of his royal patronages and duties in 2022 after Giuffre filed a sexual assault lawsuit against him in August 2021. Andrew, who had previously denied involvement with Giuffre, settled with her in February 2022.

Kate Middleton, 42, is still a working royal, and she became Princess of Wales when Charles ascended the throne. However, Kensington Palace announced on January 17 that the princess postponed her royal engagements until after Easter while she recovers from a "planned abdominal surgery."

Kate's absence in the coming weeks may feel more pronounced, given how old the rest of the working royals are compared to her and Prince William, 41. Aside from the Waleses, every working royal is 59 years old or older, which isn't ideal from a PR perspective, according to Meinzer.

"It has generally been the case that the public imagination is most focused on the younger royals in their 20s, 30s, and 40s," Meinzer told BI. "They are most focused on the royals when they are of courtship age, getting married, having babies, that kind of thing. They're not necessarily considered as dazzling or as exciting to the public when they're 60 or 70 or whatnot."

Meinzer noted that Harry and Meghan could have been assets to the king in a moment like this, thanks to their youth and charisma.

"They had that useful Hollywood energy about them that, frankly, a lot of the senior royals don't have," Meinzer said.

Prince William has trained to lead in his father's absence

As first in line for the throne, eyes will fall on William to step in for his father at engagements while the king undergoes treatment, Eric Schiffer, the chairman of Reputation Management Consultants, told BI.

As BI previously reported, William was trained his entire life to be a monarch by both Charles and Queen Elizabeth II, so it naturally falls to him to step in for his father. Likewise, because his father became king later in his life, William and Charles are aware he won't be heir as long as Charles was, making his preparation more important after his grandmother's death.

"I think you'll see William do more," Schiffer said. "It's an opportunity for him to communicate on behalf of the royal family, I think, and you'll see Camilla also play a role on behalf of the family."

Meinzer echoed Schiffer, saying that because the king is undergoing outpatient treatment, Camilla will likely be more visible to the public than if the king was in the hospital.

Schiffer also said that the royal family could instill confidence in the family by publicizing the king's remote work instead of having other royals attend in-person events.

"Show that he's working and that it's not all about hospitalization, show that he's gonna keep active," Schiffer said. "Set the expectations low for public events, but then maybe show more images and things so people can see that he's trying to be active."

The princesses of the royal family could be an asset to the king

Others may expect Charles' siblings who are still working royals, Princess Anne, 73, and Prince Edward, 59, to take on more engagements in their brother's stead.

Anne seems like a likely candidate, in particular, because of how many engagements she typically works and her public-facing role following Queen Elizabeth II's death. But as Meinzer noted, Anne is aging too.

"Anne is incredibly hardworking, and I think Anne has a lot of people's respect, but she also is a senior citizen," she said. "How much longer can we have all these senior citizens doing this much work all the time — doing hundreds of engagements a year?"

Schffer thinks if Anne and Edward take on additional duties during their brother's treatment, it will be "nothing significant," as the royal family should focus on the king's heir and his wife rather than his siblings.

Alternatively, Meinzer suggested it could be smart for the monarchy to tap Prince Andrew's daughters, Princess Beatrice, 35, and Princess Eugenie, 33, for help.

"They would bring that youthful energy," Meinzer said of the sisters.

It doesn't matter who will step into the king's shoes; it's necessary that for the royal family to remain relevant and thus survive, they'll need to band together.