Meghan Markle is to become the first fiancee invited to spend Christmas with the British royal family -- a move hailed Thursday as a sea change in the monarchy's traditionalist attitude.

Prince Harry's bride-to-be will join the royals at Sandringham, Queen Elizabeth II's private estate in Norfolk, eastern England, where the royals traditionally spend their winter break.

The US actress, 36, will have to get used to the royal family's quirky Christmas traditions -- but commentators said the fact she has been invited at all shows the confidence they have in her.

Markle and Harry, fifth in line to the throne, are due to tie the knot in May in St George's Chapel at Windsor Castle.

The couple will live in Harry's cottage in the grounds of Kensington Palace, home to his brother Prince William and his wife Kate, the Duke and Duchess of Cambridge.

A palace spokesman announced the Christmas news on Wednesday.

"You can expect to see the Duke and Duchess of Cambridge, Prince Harry and Ms Markle at Sandringham on Christmas Day," he said.

It is understood that Harry and his fiancee will stay with William and Kate at Anmer Hall, their home in the Sandringham grounds, rather than in the main house.

- 'Victorian attitudes' -

Newspapers welcomed the unprecedented invite to spend Christmas with the royals.

The Daily Mail said the move was "startling" and "represents a sea change in the Victorian attitudes which for so long have coloured the royal approach to modern life".

The announcement "underlines how swiftly the 36-year-old American is being embraced by the royal family", said The Times.

The Sun said that the move was "set to cause a new wave of Meghan mania.

"The Norfolk festivities are seen as a major test for Meghan."

But it quoted Majesty Magazine editor Ingrid Seward as saying: "Meghan will be fine. The real nitty-gritty of staying at Sandringham is being a house guest, which she will be spared."

Harry and Markle, who announced their engagement on November 27, carried out their first joint public appearance on December 1.

The public will get another chance to meet Markle when the royals go to church for the Christmas Day service. Younger members of the family walk the short distance from the house.

Markle will have to adjust to the royal family's idiosyncratic ways and customs, engrained in centuries of tradition.

The royals exchange gifts on Christmas Eve, in keeping with German practice.

However, getting a present for the Queen is not as daunting as it might seem: the monarch likes practical presents rather than extravagant ones.

Markle is reportedly an animal lover but will have to put up the with royals' tradition of going out shooting on Boxing Day.