Princess Kate's 10-year-old daughter, Princess Charlotte, played the piano at her mother's side in a pre-recorded portion of the televised concert at Westminster Abbey. The royal duo performed "Holm Sound" by Erland Cooper during "Royal Carols: Together at Christmas."

Princess Charlotte joined Princess Kate for a royal duet on Christmas Eve as part of the special "Royal Carols: Together at Christmas."

Kate Middleton and Princess Charlotte shared a heartwarming piano duet at the "Together at Christmas" carol service, playing "Holm Sound."

The mother-daughter duo taped a performance inside Windsor Castle for the television broadcast of the Princess of Wales’s Christmas carol.

Princess Charlotte's latest public appearance has many royal fans noticing that she's becoming so much like her late grandmother, Princess Diana.

The Princess of Wales and Princess Charlotte shared a surprise (and poignant) moment at the royal Christmas carol service.

Catherine, the Princess of Wales, and her daughter Princess Charlotte teamed up for a special duet. On Christmas Eve, the official social media accounts for the Prince and Princess of Wales released a video that showed the royal mother-daughter duo performing a special rendition of Holm Sound by Erland Cooper on the piano.

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