Child psychologist Dr Catherine Wikholm told the Daily Express: “The parent should respond to questions calmly and honestly in an age-appropriate way – keeping details to a minimum, especially if some of the details are uncertain.

“It can be a lot for a young child to process and it is important to not give too much information at once but let them know they can ask further questions.”

The children are not believed to have yet visited their mother in hospital – another smart move on William’s part, according to Dr Wickholm.

Instead, she suggested, they are likely to have had a video call and made her get-well cards.