Tom Walker has hailed Catherine, Duchess of Cambridge as a "really great musician."
The 30-year-old songwriter was accompanied on piano by the duchess for a surprise performance of his song 'For Those Who Can't Be Here' at on ITV's 'Royal Carols: Together At Christmas' special and he has told how he and the 39-year-old royal had a "top secret rehearsal" before the show.
He said: "She's fantastic, a really talented musician. We had a top secret rehearsal to make sure we were compatible, it was at Metropolis Studios."
The 'Just You and I' hitmaker then went on to explain how the collaboration came to fruition when he first met Catherine when he performed his addiction-themed song ''Leave a Light On' at an event for drugs charity The Forward Trust.
Speaking on UK TV show 'Lorraine', he explained: "We did a charity event together and got chatting and I was approached after that to ask if I could play the carol service. The Duchess' team asked if she could join me on piano for the concert live, incredible."
Tom later explained that he and Catherine - who has three children with husband Prince William - rehearsed the song "nine times" before taking to the stage, by which time claimed she had "absolutely nailed it."
He said: "We rehearsed the song like nine times and by the end of it she'd absolutely nailed it, and then she went away for a couple of days and practiced it, and then we finally got to do the recording of it."
In terms of his plans for 2022, the star revealed that he is set to go straight back into the studio and aiming to take his music on tour in the latter half of the year.
He said: "I'm back in the studio first thing next week and a tour at the end of the year so I'm excited. It's exciting to know things are hopefully going to be starting up soon."
