United Kingdom, Dec. 28 -- Catherine, Princess of Wales and Princess Charlotte "didn't need direction" for their piano duet because they were "so good".

The 43-year-old royal and her 10-year-old daughter sat side by side at the piano for a performance of Holm Sound, which aired as part of the screening of the Together At Christmas carol concert on Christmas Eve (24.12.25), and the piece's composer Erland Cooper admitted it was "such a surprise" to be invited to the filming of the duet at Windsor Castle.

Erland told BBC Breakfast: "I'd had a chat with the princess earlier in the year and I knew she enjoyed playing this piece of music with family.

"It was a big surprise to be invited to Windsor Castle and hear it performed by a pair of p...