Princess Kate Middleton's annual "Together at Christmas" carol service featured an extra-special performance. Kate, 43, and daughter Princess Charlotte, 10, opened the concert with a piano rendition of Erl and Cooper's "Holm Sound." "Love and connection through music 💕," the Princess of Wales captioned footage of the duet via Instagram on Wednesday, December 24. In the prerecorded clip, Kate and her daughter twinned in navy as they sat side-by-side on a piano bench.