Kate Middleton’s Trooping the Colour appearance took a toll on her health amid cancer battle: expert

Kate Middleton’s defiant return to the spotlight at Saturday’s Trooping the Colour ceremony has taken a toll on her health, according to a royal expert.

The Princess of Wales, 42, looked stunning as she joined the royal family for the King’s birthday celebrations on the Buckingham Palace balcony to watch the royal flypast.

But according to royal expert Katie Nicholl, the physical toll of the event impacted the royal’s health.

“The princess has this sort of swan-like quality about her — she’s sort of gliding on the surface — but beneath the water, I think often she’s paddling quite frantically,” Nicholl told “Entertainment Tonight.”

“I can only imagine that a huge amount of preparation and time and effort and energy will have gone into Saturday’s appearance.”

“She was on her feet for a long period of time,” she continued. “There was a moment where she was watching the parade… and was offered a seat, which she gratefully accepted.”

“That’s just a bit of an acknowledgement that she is not as strong, not as fit, as she was before she went into this treatment,” Nicholl added.

The Post has reached out to Kensington Palace for comment.

On Saturday, the Princess of Wales delighted fans by appearing alongside her husband, Prince William, and King Charles to watch the traditional military flypast with her three children.

After the Red Arrows shot past the palace, spraying the colors of the Union Jack flag behind them, Middleton and her family waved to the crowd below.

Despite the fact that the mom of three is currently undergoing chemotherapy, Nicholl noted that Middleton, 42, “looked impeccable.”

“If you didn’t know that she was going through cancer treatment, you would never have guessed,” she said. “I think a day like Saturday, where she knows the eyes of the world are on her, there is a huge amount of scrutiny that will take its toll.”

“I think we can probably imagine that she probably had a long and well deserved rest afterwards. I don’t think we can expect to see her in public for a little while,” she said, adding that it’s “going to take some recovery from.”

As for the Princess’ decision to show up at the ceremony, Nicholl said that Middleton made that call “alone.”

“There was no pressure on her from anyone. She really wanted to do this,” she said. “She turned a corner in her treatment… When she turned that corner, I was told that Trooping was a goal for her.”

“She was given the sign-off by her medical team. She spoke to her father-in-law about attending and to Prince William. They were fully behind her,” the royal expert added. King Charles announced his own cancer diagnosis in February.

Middleton appeared at the splashy military ceremony in honor of King Charles’ birthday after announcing Friday that she was currently well enough to attend.

Following her appearance, Nicholl said that “there’s a great sense of pride” in Princess Catherine.

“I think she felt very much that she needed to be there,” she said. “The children looked so happy and relaxed having their mother there.

“It was important, I think, for the Princess of Wales to be there to support her father-in-law, to be there for her family, and to be there for the nation to send out a really important message that she’s doing OK.”