The Princess of Wales and Princess Charlotte
YT/ The Prince and Princess of Wales

Princess Charlotte sat beside her mother at a grand piano in Windsor Castle last week, their hands moving across the keys in perfect harmony.

The 10-year-old joined Princess Kate to play a heartfelt rendition of 'Holm Sound' by Scottish composer Erland Cooper. The performance opened the Christmas Eve broadcast of the royal family's annual 'Together at Christmas' carol service, which aired on Wednesday on ITV1.

It's Kate's first Christmas celebration since revealing in January that she's in remission following her cancer diagnosis last March.

A Piece Close to Home

The song choice wasn't random. Cooper, a producer and multi-instrumentalist from Scotland's Orkney Islands, composed 'Holm Sound' as a tribute to his own mother.

The palace said it's become one of Charlotte and Kate's favourite pieces to practice together. Cooper himself showed up during filming to coach them through the recording, ITV News reported.

The mother-daughter pair filmed the segment in Windsor Castle's Inner Hall, according to CNN. Charlotte looked relaxed throughout, occasionally glancing at her mum with a smile.

Whilst they played, Kate's voice narrated over the music with reflections on what Christmas truly means.

Christmas isn't about grand gestures, she said. It's found in the small moments. ABC News quoted her saying: 'A moment of listening, a word of comfort, a friendly conversation, a helping hand.'

Charlotte's Piano Journey

Charlotte has been learning piano for years now. Kate mentioned her daughter's lessons during a 2021 chat with concert pianist Lang Lang.

Lang later recalled Kate telling Charlotte that with enough practice, she could play like him one day. 'I'm sure she's good,' Lang told People at the time.

This year, Prince William gave an update on all three children's musical education during an appearance on Apple TV's 'The Reluctant Traveler'.

'They're trying to learn musical instruments,' William said, Today reported. 'I'm not sure how successful we're being with that.'

Judging by Wednesday's performance, Charlotte seems to be doing just fine. Her brothers Prince George, 12, and Prince Louis, 7, are also picking up instruments.

Kate's Public Piano Moments

Playing piano in public isn't new for Kate. She surprised viewers during the 2021 'Together at Christmas' service when she accompanied singer-songwriter Tom Walker on his track 'For Those Who Can't Be Here'.

That wasn't her only televised performance. She also played during the opening of the 2023 Eurovision Song Contest.

This year's duet with Charlotte felt different, though. ITV News said Kate wanted the performance to embody the themes of love and connection she'd written about in her letter for the service.

Mission accomplished.

The Full Service

Westminster Abbey hosted the carol service on 5 December. This year's theme celebrated love in every form, CNN reported.

Hannah Waddingham, Griff, and Katie Melua delivered musical performances. Prince William, Kate Winslet, and Chiwetel Ejiofor gave readings. The abbey's famous choir sang traditional carols whilst decorated trees lined the entrance.

Kate closed her narration with a message of gratitude.

'As the year draws to a close, I hope this season brings you moments of peace and clarity,' she said. 'Thank you for the warmth you have given and the kindness you have shown and the quiet, constant light you bring to others. Wishing you a very happy Christmas.'