Duchess of Cambridge shares adorable photo of her family to celebrate Christmas Day

Prince William kissing Louis in a picture taken by Kate Middleton. (Kensington Palace)

The Duchess of Cambridge shared an adorable snap she took of her family to celebrate Christmas Day.

The official Kensington Palace Twitter account posted the photo online and said it had been taken by Kate Middleton in Norfolk earlier this year.

In the intimate picture, Prince William poses with all three of the couple’s children; George, Charlotte and Louis - and the Duke can be seen planting a kiss on his youngest son’s cheek.

Earlier in the day, Prince George and Princess Charlotte joined the Queen at the royal family’s traditional Christmas Day church service on her Sandringham estate for the first time.

The Duke and Duchess of Cambridge with Prince George and Princess Charlotte after attending the Christmas Day morning church service in Sandringham, Norfolk. (PA)

The youngsters walked the short distance from Sandringham House to St Mary Magdalene Church with their parents.

George, six, and Charlotte, four, appeared to be in good spirits as they attended the church service.

Prince Louis, meanwhile, who is just one year old, stayed at home.

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The Duke of Edinburgh, 98, who was discharged from hospital on Christmas Eve, was at Sandringham but did not attend church.

He had spent four nights at the King Edward VII Hospital in London to receive treatment for a “pre-existing condition”.

The Duke of York, who has had a tumultuous end to the year after his disastrous appearance on the BBC’s Newsnight programme, walked side by side with Charles to a private service at 9am but did not attend the 11am service.

Andrew remained at Sandringham House to spend time with the Duke of Edinburgh, a source said, which was the Duke of York’s personal decision.

The Duke and Duchess of Sussex were also absent this year, instead opting to spend seven-month-old Archie’s first Christmas with the duchess’s mother, Doria Ragland, in Canada.

The 93-year-old Queen, wearing a red coat and hat, arrived at the church in a maroon Bentley with the Duchess of Cornwall.

Back at the house, the family traditionally indulge in turkey, reared at Sandringham, before settling down to watch TV, including the Queen’s Christmas Speech.