Prince William and Princess Kate love sports, but usually enjoy the very British sports of soccer (football), rugby, tennis, polo, and cricket.

Surprisingly, however, the Prince and Princess seemed totally out of their element when they watched a Boston Celtics vs. Miami Heat basketball game as part of a three-day trip to the United States.

"Kate was clearly having a wonderful time with William at the basketball game, as she chatted merrily with him and also seemed engrossed in everything that was happening, making very genuine gestures of happiness and joy." Darren Stanton, body language expert and royal commentator, told Marie Claire on behalf of Slingo (opens in new tab).

"Of the seven main facial expressions - joy, sadness, anger, fear, surprise, contempt, and disgust - joy is the emotion that is most deceptive to people.

"In Kate's case, however, she always smiles a smile that shows real, genuine emotion, communicating that she is happy to be in that environment and talking to other people.

For Stanton, the appearance of this royal couple proves how far the royal couple has come in terms of owning the room.

"Comparing Kate and William to a few years ago, they seemed much more nervous and dependent on each other for support," he says.

"Now they have gained so much confidence, both as individuals and as a royal family.

"At the Boston Celtics game, you could see a lot of lively hand gestures when Prince William was talking to someone by his side. Prince William is usually a quiet person and his gestures are reserved. So this change tells me that he is completely at ease with his surroundings, very comfortable, confident, and passionate.

"Similarly, Kate was relaxed and seemed very natural, laughing and joking with those by her side.

The Welsh couple sat courtside at the game along with Boston Mayor Michelle Wu and Massachusetts Governor-elect Maura Healey, and Princess Kate even held the ball as Prince William looked down at it in confusion. The result is one of the most stunning photographs ever taken.