Prince George was not present during the royal family's traditional Christmas Day church service.

The Duke and Duchess of Cambridge, who is five months pregnant with her second child, apologised to crowds for leaving their 17-month-old son at home.

The Duchess of Cambridge told an eight-year-old Maddison Neal, who gave Kate a Milky Bar selection box for George, that the toddler was with his nanny.

"I'm sorry we didn't bring George but you would have heard him in the church," Kate said.

William also told the crowd of about 2,000 well-wishers that their child was well but had been left in the nursery due to the cold weather.

"But they were looking forward to going back to see what destruction he's created. George was having a lovely day," Kim Dawson, who had a chance to chat with Prince William with her mother, told the Mail.

The royal couple, who walked to church hand in hand, joined the Queen and other members of the family, including Duke of Edinburgh, Prince Charles, and Prince Harry for the service at St Mary Magdalene Church near the private Sandringham estate in Norfolk.

Kate's parents, Michael and Carole Middleton, and her siblings, James and Pippa, were also spotted among the guests to the church that day.

Camilla, the Duchess of Cornwall, was also not present among the congregation due to a bad back.

After the service, the Queen did not stop to take flowers from waiting children and instead went straight to her car, while the rest of the royals stayed and spoke with the crowds.

The Duke and Duchess of Cambridge, together with baby George and the Middletons, were spending the Christmas holiday at Anmer Hall, the couple's new country house located on the Sandringham estate.

Norfolk locals said they have seen the Duchess out and about shopping and at local parks with George. According to the Mail, the young prince even toured Santa's Magical Journey at Thursford the other week.