The royals have all sorts of protocols governing them when they're out on official business, but at the 2022 Top Gun: Maverick premiere, Tom Cruise ended up breaking one.
In an act of generosity, the Hollywood superstar - who is an unexpected guest during the Coronation Concert - took the Princess Kate by hand as she ascended some stairs, however it has long been rumoured that you aren't supposed to touch a royal.
In fact, it's well known that you were only allowed to take Queen Elizabeth's hand if she offered it first.
The moment during the movie premiere was very sweet, but it appears that Kate was aware of the protocol, as after Tom released her, she moved her bag into the hand that he had been holding, so he couldn't take it again as they ascended some more stairs.
There are plenty of rules that members of the royal family must follow when they are out and about, including the need to keep PDAs to a minimum, which is likely why William didn't take his wife by the hand as they went up the stairs.
HELLO! magazine's royal editor Emily Nash previously said: "The Duke and Duchess are almost always seen in photographs taken during official engagements so they are at 'work' and it would be unprofessional to hold hands.
"They also need to shake hands with a huge number of people as they meet then, so aside from being on duty, it wouldn't be very practical!"
"We know they are very affectionate and that sometimes comes across during more light-hearted moments, at sporting events or similar, but you wouldn't expect them to put that on show while in more formal situations."
Royal rules also prohibit members of the royal family from taking selfies or signing autographs, and so while we're sure the cast of Top Gun wouldn't have minded a quick photo, the only photos taken were by professional photographers at the premiere.