To highlight the initiative, the duchess joined what was described as a “screen-free afternoon of games, friendship bracelets, colouring – and some frank talk about social media” in Santa Barbara, California, on October 2 to test out the curriculum.

May said: “Ultimately, we thought the best way to do that was to create a space of vulnerability … we talked about what it really means to grow up in this digital age.”

The duchess has spoken previously about how the majority of the “bullying and abuse” she received on social media took place during her pregnancies with her children, Archie and Lilibet.

“You just think about that and really wrap your head around why people would be so hateful – it is not catty, it is cruel,” she told an event in Texas in March.

The duke and duchess have been campaigning for more rigorous controls of the digital sphere. In August, they launched the Parents’ Network, a resource for parents whose children have experienced harm on social media.

Last month, Prince Harry gave a passionate speech at the Clinton Global Initiative in New York in which he took his phone from his jacket pocket and said: “My lock screen is a picture of my kids. What’s yours?”

Images of young people on mobile phone lock screens appeared on the large screen behind him as he went on: “These children and thousands more meant the world to their families. Their beautiful faces you see before you, their smiles, their dreams, all lost, all too soon, and all because of social media.”

The duchess was the subject of a bullying complaint herself in 2018, when the Sussexes’ then press secretary wrote to their private secretary outlining his concern “that the duchess was able to bully two PAs out of the household”.

The findings of an official investigation into the way the palace handled the allegations was kept secret.