What Prince Harry and Prince William's Body Language Said During King Charles' Coronation: Expert (Exclusive)

Body language expert Darren Stanton analyzed the royal family's big day for ET.

Prince Harry's appearance was a major focus at the coronation of his father, King Charles III, on Saturday, and all eyes were on the estranged royal as he attempted to stay in the background during the lavish ceremony.

However, with cameras capturing every moment of the historic proceedings, several of the prince's facial expressions -- from stares to smiles to an unexpected grimace -- went viral as fans analyzed every moment of his royal return.

Body language expert Darren Stanton spoke with ET on Monday to analyze some of the expressions from the royal family over the course of the coronation weekend. 

"The main thing that I look for are microexpressions," Stanton explained. "A lot of people don't realize that we have a thing called leakage, so no matter how well-trained somebody is, it gives us a sense of the real emotion that the person is experiencing."

"With Harry, we see sadness, we see the eyebrows come together, we see the mouth droop," he added of the prince's general demeanor. "He was experiencing a combination of frustration, anxiety, a little bit of sadness at the fact that he wasn't fully involved in the process. I think he felt very uncomfortable."

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Some of that anxiety, Stanton explained, could have come from the fact that Harry was flying solo at the event. While he entered Westminster Abbey with his cousins, Princess Beatrice and Princess Eugenie, and their respective husbands, Harry's wife, Meghan Markle, stayed home in California, leaving the prince to face his royal return on his own.

"I mean, the thing is, Prince Harry is still incredibly popular in this country -- although a lot of people don't agree with what he did by leaving the U.K. and going to the States," Stanton noted. "People are probably not as warm -- even though they're still supportive, they're probably not as warm to him as they once were."

"I think he feels quite isolated," he added. "I think he's thinking, you know, 'Gee, I used to be part of all this.' And I think he's homesick. He's homesick for his family, homesick for London, you know, he's homesick for all that pomp and circumstance. So really, sadness and isolation -- I think that's what I got from his body language."

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While Harry didn't have any contact with his father or Prince William during the ceremony, cameras did capture him looking over at his older brother during the ceremony. Due to his royal demotion, Harry sat in the third row with his cousins, while the Prince and Princess of Wales sat with their children in the first row.

"These two brothers have been through so much together, and I think deep down they still love each other," Stanton speculated of the pair's relationship. "I think even through William's incredibly frustrated with the way things have gone, I think deep down I'm of the belief that they'll come good, they will kind of reconcile their relationship."

"In terms of that look," he added, "I just think Harry felt left out, a little bit out of the loop, a bit isolated and really yearning and wishing that he could be part of it with his brother."

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Viewers saw a few smiles from Harry through the coronation ceremony, but none seemed as wide or authentic as when he departed the ceremony solo, hopping into a black BMW to fly home to California for son Archie's 4th birthday.

"A real smile is the whole face, where a fake smile is only the bottom half of the face gets engaged," Stanton explained. "I saw plenty of fake smiles when he was in the Abbey, but certainly checking into the airport we saw lots of authenticity and his happiness."

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"That's the one thing about him -- when he's out and he's talking to press or when he's at the Invictus Games, he tends to have this inner confidence. It comes out [when he] can be his own person," he added. "Certainly back here, with all these friends and family, he probably [felt] a little bit stifled and couldn't be himself."

Thanks to his role as heir to the throne, William played a significant role during the coronation, sharing an emotional moment with his father as he pledged his loyalty to the new king, which Stanton called "the most powerful scene of the whole process."

But the body language expert also called attention to the ways in which the Prince and Princess of Wales have started to buck royal tradition with the way they carry themselves.

"They're now doing gestures and interacting with people in ways the queen would never do," he explained. "They go to a school, they're happy to sit cross-legged on the floor with the kids. At the [coronation] concert, Kate and William were kind of kneeling down to the children's eye line, so they felt connected as well. There's certain things I see in both of them that says they're going to be very different monarchs."

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For William, perhaps the most important sign is that he's begun to shake of the nerves of a young royal and embrace his position as the next king. Stanton said he's of the belief that William's confidence has "skyrocketed" in recent months.

"William, a few years ago, used to do a gesture he inherited from Charles, which is what we call a pacifying gesture," he explained. "He would tuck his hand into his jacket, or he would play with cufflinks, or he'd pretend there was lint on his suit. Any gesture where we touch ourselves is a self reassurance gesture. William used to do this a lot when he was feeling self-conscious, but certainly over the coronation and in recent months, we've noticed that's decreased, so that tells me that he's now kind of found his footing and embraced the fact that he's gonna be king one day."

Although the actual anointment during the coronation ceremony was not broadcast publicly, plenty of special programming and footage from the ceremony is available to watch on CBS and Paramount+. Audiences can also view coverage on CBS News, including the coronation concert featuring Katy Perry and Lionel Richie. Additionally, others can watch the coronation online on these streaming platforms.