King Charles' Trooping the Colour appearance displays monarch's resilience amid cancer battle: expert

For King Charles III, the show must go on.

The British monarch, who was diagnosed with an undisclosed form of cancer earlier this year, will be attending Trooping the Colour on Saturday. The event is the second in his reign, and the first since his diagnosis was made by Buckingham Palace.

"Queen Elizabeth used to say, ‘I must be seen to be believed,’" Christopher Andersen, author of "The King," told Fox News Digital. "That meant she had to get out there in front of her people and show them that the monarchy was healthy, moving forward and all is well with the country. It’s the symbol of the country."

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"Now that’s the king’s job," Andersen shared. "King Charles is battling cancer, so he has to show up and really make it appear that everything is OK within the House of Windsor."

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According to Andersen, the tradition of the monarch having two birthday celebrations — his actual birthday and the public festivities — dates back to King Charles II, who ruled from 1660 to 1685. Trooping the Colour became an annual event during the reign of King George III, who ruled from 1760 to 1820.

While Charles will attend the event amid his cancer treatment, this year’s festivities will look very different. While he previously rode on horseback, this time he will be seated in a horse-drawn carriage alongside Queen Camilla.

"He wanted very much to be out there [on horseback] and convey the message that everything was going well and not to worry," said Andersen. "His doctors have told him this year he can’t do that… He won’t do it the way he wants to do it, which is on horseback."

Andersen said that it was important, now more than ever, for the king, 75, to put the monarchy’s strength on full display. His daughter-in-law, Kate Middleton, confirmed on Friday that she plans to attend the parade. It will mark the mother of three’s first public appearance since she announced her cancer diagnosis.

"His Majesty is delighted that the princess is able to attend tomorrow’s events, and is much looking forward to all elements of the day," said a Buckingham Palace spokesperson, as quoted by People magazine.

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Andersen noted that the king had been determined to follow his late mother’s mantra — keep calm and carry on.

"He does want to show up because he recognizes the symbolism of the moment," Andersen explained. "Look, the monarchy is under siege right now. It has a major problem with not only the king’s cancer diagnosis, but also the Princess of Wales’ cancer diagnosis. 

"Prince Andrew had to step out of the picture [following his Jeffrey Epstein scandal]. Prince Harry and Meghan Markle have been shoved into the shadows here. There’s no progress being made there… between Harry and his brother and his father. So right now, the king is sort of on the ropes."

"I think he has to show people that all is well," Andersen continued. "And that balcony scene is so important. At the end of where they have the flyover, all the royal family appears. The senior royals appear on the balcony."

One thing the public won’t likely see is the king’s comical quirks. In his book, Andersen detailed the royal’s alleged mannerisms, which have raised eyebrows over the years.

"This is one of the quirkiest monarchs we’ve ever had," Andersen chuckled. "He still travels with his pet teddy bear, the one he had as a child, and that only his nanny could ever mend. It’s a bit of a mess at this stage. And I do write about all of his preferences, how the silverware when he eats has to be at a certain angle, that his valet has to lay out his clothes in a certain way and that he will travel with his own chef, that sort of thing."

"He has his own toilet seat… that he takes with him, an upholstered white leather toilet seat," Andersen alleged. "Apparently, he finds it very comfortable… and hand towels. He brings all of his own hand towels and his own toilet paper with him when he goes abroad. But look, you are not going to see any of that during [Trooping the Colour]. This is a very formal ceremonial affair. It’s supposed to honor the military. That’s the main reason for it. That’s why you have the fantastic flyover of all those vintage jets and state-of-the-art aviation that Britain is so famous for."

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"You won’t see it, but there will be a lot of silly things happening behind the scenes," Andersen added.

According to Andersen, the king wants the celebration to focus on the monarchy’s future, as opposed to the ongoing health battles rocking the palace. And with Charles long wanting a more slimmed-down monarchy, all eyes have been on his reign.

"He had these very specific plans on how to do it," Andersen claimed. "He wanted to take certain members of the royal family and take them off the payroll… because he felt there [were] too many people that the crown was having to support and that it was too confusing. He wanted to focus on… a core bunch. 

"Unfortunately, he couldn’t have predicted that Harry and Meghan would depart, but that Andrew would create a scandal for him. [Andrew's] relationship with Jeffrey Epstein, of course, made it impossible for him to continue as a working royal. And so, Charles was left really with this very small group."

"Now, a major part of the royal family… the most popular member of the royal family, the woman who symbolizes the future of the royal family, is seriously ill," said Andersen, referring to the Princess of Wales. "I think, if anything, now he feels he needs all the help he can get… That’s why we see Prince Edward and [his wife] Sophie stepping up… But it’s a really rough time for Charles."

While the Trooping the Colour will be a joyous time for both the royal family and Britons, Andersen believes Charles will have a different approach to his reign as he continues treatment.

"[Charles] is the kind of person who does have a spectacular temper," Andersen claimed. "I have written about this extensively. But he seemed to be keeping it all under control. Maybe perhaps facing this issue of mortality for the first time… it’s something he hadn’t expected. 

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"Talk about irony here. You wait your entire life for this role, and then you’re in it for less than two years and told that now you have to battle for your life. I think that’s something none of us could ever have predicted. But he’s… put up a pretty brave front and soldiered on."

The Associated Press contributed to this report.