The future Queen asked singer Tom Walker to take part in her Together at Christmas carol service — and suggested she accompany him!

Kate Middleton.Credit : Alex Bramall

Kate Middleton “completely nailed” her first public performance on the piano.

Just ask singer Tom Walker, whom she accompanied in a surprise moment during the broadcast of her Together at Christmas carol service broadcast.

“Without doubt, it was a once-in-a-lifetime experience,” Walker said of their duet, which aired Friday night in the U.K. “I thought she absolutely smashed the performance; it’s not easy to just jump behind a piano with a bunch of musicians you’ve never played with before and record live takes to camera, but she completely nailed it.”

Added Walker, “She’s such a lovely, kind and warm-hearted person and she took the time to thank everyone personally for the opportunity to play together. It was a crazy pinch-yourself kind of day for me, to be in such a beautiful venue playing alongside the Duchess with my band and a string quartet. I certainly won’t forget that in a hurry!”

According to a royal source, the idea for the performance came from the Duchess of Cambridge herself.

She learned the piano as a child and has taken “great comfort” in playing music throughout the pandemic. Then she attended a Forward Trust event this October, where met Walker, 30, and heard him perform “Leave a Light On,” his song about the struggles of those experiencing addiction.

Kate Middleton.Alex Bramall

She asked him to play at the carol service because his holiday song “For Those Who Can’t Be Here” had “such pertinence for so many this year.” It also “struck a chord” with Kate, 39, who suggested herself to accompany the hitmaker.

“Music was very important to the Duchess during the lockdowns,” says the royal source. “She also recognizes the powerful way in which music brings people together — especially during difficult times. For these reasons, she was keen to be part of Tom’s performance in this way.”

Alex Bramall

Months later, producers created a magical scene at Westminster Abbey’s Chapter House for the performance, which was pre-recorded the day before the December 8 service. The new musical duo had rehearsed the song together once in London and then recorded it over a “couple of takes,” the source adds.

Alex Bramall

The Duchess’s prowess on the keys clearly impressed the Scottish musician — he shared a smile with her at the end of the performance and said it was an honor playing alongside her.

Added Walker, “My mum had a total freak-out when she saw it on the telly. I know this song will resonate with a lot of people this Christmas and my heart goes out to anyone raising a glass around the table remembering those who can’t be with us.”