Kate Middleton, Prince William, and Prince Harry previously launched the Heads Together campaign as part of the Royal Foundation. But during a previous interview, it was revealed that it was actually the Duchess of Cambridge who came up with the idea.

During an interview with Tina Daheley during the Royal Foundation’s annual forum last year, the Duke of Sussex said that Middleton shared her concept with him and his brother by writing her thoughts on the back of a cigarette pack.

Daheley thought that Prince Harry was joking, but he said that it is true. The Duke of Cambridge then credited his wife for her huge contribution to the campaign.

“As alluded to earlier, Catherine was the one who put this, sort of, joined the dots together for all of us. She’s the one that came up with the idea and the concept in a way because Harry and I never thought about doing a campaign as such before and when you tackle mental health, it’s very difficult to know,” Prince William said.

The dad of three went on to say that creating a campaign was one of the quickest and most effective ways to make a difference and to make an impact. The three of them were on the same page with Heads Together, and Meghan Markle eventually joined them when she became part of the royal family.

But just one year after the royal couples attend the annual forum, it was announced that they would be splitting. Prince Harry and Markle have since launched their own foundation called the Sussex Royal Foundation. Prince William and Middleton, on the other hand, is still handling the Royal Foundation.

Meanwhile, the royal couple’s split was deemed necessary because Prince William and Prince Harry are on different paths at the moment. The Duke of Sussex also confirmed this during his interview in the ITV documentary “Harry & Meghan: An African Journey.”

Prince William, Prince Harry, Meghan Markle and Kate Middleton Pictured [L-R]: The Duke of Cambridge, Duke of Sussex, Duchess of Sussex and Duchess of Cambridge arrive at Westminster Abbey to attend a service to mark the centenary of the Armistice on Nov. 11, 2018 in central London. Photo: Paul Grover/AFP/Getty Images