Prince William and Kate Middleton have had a busy week, welcoming Donald and Melania Trump to the UK ahead of their state visit and later joining King Charles and Queen Camilla at a glittering state banquet. But beyond the formalities, it was a small, personal gesture that caught the public’s attention: a rare photo of the couple holding hands, shared on their official Instagram account.

As the Prince and Princess of Wales, William and Kate are not only preparing for their future roles as king and queen but also carrying a heavy load of responsibilities in the present. When King Charles was diagnosed with cancer, William stepped in to take on additional duties. At the same time, Kate has been steadily recovering from her own cancer battle and has now returned to a more regular rhythm of royal life.

The Trump state visit marked a significant moment on the royal calendar. On their arrival at Windsor, William and Kate welcomed the former U.S. president and first lady before joining the monarch and Camilla in hosting them for a lavish banquet. The couple looked radiant at the event, but it was the photo shared afterwards — William and Kate holding hands — that sparked the biggest reaction.

Why the Waleses Rarely Show PDA

Public displays of affection are unusual for William and Kate, and experts say there’s a reason for that. Body language expert Darren Stanton explained to The Sun that it all comes down to protocol.

“Kate and William play a very important role in the royal family now as the Prince and Princess of Wales,” Stanton said. “As they are next in line to the throne and preparing to become king and queen themselves one day, they follow the traditional royal protocols of the late Queen.”