The service this year – which has already been filmed – is part of the Shaping Us campaign, which focuses on the role played by people shaping future generations and the importance of early years, Kensington Palace said.
“Sharing some festive memories this Christmas because #ShapingUs is all about the vital importance of our early years,” the Prince and Princess of Wales said in a post on social media site X.
The palace said the royal couple will be inviting others to share images of their earliest Christmas on their social media channels in the lead-up to Christmas Eve.
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As they walked into the abbey, Prince Louis, five, Princess Charlotte, eight, and elder brother Prince George, 10, posted Christmas cards in a special postbox, containing messages for children who might be struggling this Christmas, something open to all youngsters attending.
Inside the church, the trio carried candles, as did other children, and at one point, Louis reached across and extinguished a smiling Charlotte’s candle.
The carol service will air on 24 December on ITV at 7.45pm.