Prince William landed in NYC on Monday (Image: GETTY)

       Prince William arrived in New York City on September 18, with one body language expert claiming that the senior royal appeared "anxious".

       The heir to the throne is currently in the US, with royal fans surprised that his wife, the Princess of Wales, skipped the trip.

       William, 41, is set to promote the environmentalism initiative, which he and David Attenborough launched in 2020.

       The royal will also be attending the Earthshot Prize Innovation Summit later today, September 19.

       According to a body language expert Judi James, William has shown signs of "some feelings of anxiety" just hours into his solo visit.

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       William appeared 'anxious', a body language expert said (Image: Getty)

       Discussing his posture and appearance, Ms James told the Mirror: "That left hand fiddling with his jacket forms a partial barrier ritual, suggesting William is experiencing some feelings of anxiety."

       Ms James continued: "But otherwise his body language suggests a desire to look informal, un-regal and rather sweetly upbeat here."

       Despite this, she added that his appearance showed signs of his younger self, stating: "His open-mouthed, rather excited smile and wave is a show-stopper because he’s regurgitated the shy, bashful but also playful facial expression and look that he wore so much as a child.

       "The wave is friendly and, again, a royal and a celebrity-free gesture, with the hand held low to connect in a more accessible, down-to-earth way."

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       William landed in NYC on Monday (Image: Getty)

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       Speaking of how William interacted with a man that was talking to him during the visit, Ms James said: "William also listens intently as the man speaks to him...with his hands clasped low in front of his body and his mouth puckered slightly to signal he’s very much there to listen and learn."

       Taking to X - formerly known as Twitter - William stated how it was "so good to be back in the United States".

       On the account that he shares with Kate, William wrote: "No one does optimism and ingenuity like the American people, so it's only right we unveil this year's @Earthshotprize Finalists in New York City."

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       Kate has been in London today, September 19 (Image: Getty)

       Although there was no official announcement that Kate wasn't due to attend, many fans expected her to as she was in attendance last year.

       Taking to social media, one fan wrote: "So sad. We wanna see Princess Catherine." Another simply added: "Noooo" with a crying face emoji.

       Despite this, another pointed out that the point of the trip was for William's solo project, stating: "It’s her husband’s project and she isn’t required to be there. Let’s face it, we all just want her to go so we can see a pretty dress."

       Today, September 19, Kate has ventured into London for her own visit to Streets of Growth, a not-for-profit youth intervention charity based in East London.

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