The Sweet Reason Kate Middleton Didn't Join Prince William for His New York Trip

"This is a fleeting visit. And the couple tend not to travel abroad together unless they have to, because, of course, they're juggling childcare and schooling for three children," Nicholl toldET, referring to Prince George (10), Princess Charlotte (8) and Prince Louis (5). "This is William's project... This summit was something that William planned to always do on his own."

She added, "I think this is a very positive trip for Prince William, and most importantly, really establishes him as a statesman on the world stage."

As it turns out, the princess also had an outing to attend in the U.K. On Monday, she visited the Royal Naval Air Station (RNAS) Yeovilton in Somerset, where she made her debut as theCommodore-in-Chief of the Fleet Air Arm.

During her visit, she toured the Air Traffic Control tower, participated in some training exercises and met with staff members.

While Princess Catherine didn't join Prince William for his New York trip, she's proven to be one of the biggest supporters of his Earthshot Prize initiative. In fact, just last year, the royal stunned in green when she joined her husband for the award ceremony in 2022.

When shepresented the awardfor "Clean Our Air," she said, "To breathe clean air is something so many of us take for granted. But sadly for millions of people around the world, it is not a given, from smog enveloping cities to the impact seen in nature. Air pollution poses a threat that knows no borders."

She added, "But there are reasons to be hopeful. I'm delighted to see the work of our three finalists and their solutions to clean our air."

We're sure the princess is cheering Prince William on from across the pond.

Stay up-to-date on every breaking royal family story by subscribinghere.