Prince George and Prince Charlotte's Christmas milestone

Prince George and Princess Charlotte will appear at the Christmas Day service with their parents this year. Photo / Getty

Prince George and Princess Charlotte are set to make their Christmas debut this year.

The Sun revealed that George, six, and Charlotte, four, will walk to church on Christmas Day with their parents William and Kate for the first time this year.

The walk from the Queen's Sandringham house, where the royal family traditionally celebrates Christmas, to St Mary Magdalene Church is always a big event.

A royal source said: "It will be so sweet. George and Charlotte will make their Christmas debut, as long as they're both on good form on the day.

Kate and William feel their children are ready for the Christmas appearance, which is a rite of passage for the royals. Photo / Getty

"It's the picture all royal fans want to see. The royals walking to church on Christmas Day is a rite of passage and so William and Kate didn't want to expose their children too early, but they feel they're old enough now."

And with all the negative media attention on Prince Andrew, debuting the royal children on Christmas Day is something of a strategic move.

"These pictures will also emphasise the positive future of the royal family," the spokesperson said.

"Ultimately it's the Queen who decides who does what on Christmas Day as it is a formal engagement.

"So perhaps she is conscious that this is a positive way in which to change the narrative."

Andrew will also attend church with the family, but it's understood he will go with the Queen in a car rather than walking with the rest of the royals.

While it's the royal children's first Christmas appearance, their uncle Harry and aunt Meghan won't be attending this year. Photo / Getty

Prince Louis is still too young to attend at 18 months, so William and Kate plan to leave him at home with Kate's parents while they attend church.

Prince William's first Christmas appearance was in 1987, when at five years old he appeared at St George's Chapel in Windsor cheerfully waving at photographers.

Four-year-old Harry joined in the following year for the Sandringham Christmas Day Service.

The Sun earlier revealed that Harry and Meghan won't be joining the royals for Christmas this year, as they're spending it with Meghan's mother Doria Ragland.