Step by elegant step, Meghan Markle is transforming the Royal Family. Yesterday's announcement by Buckingham Palace that Prince Harry's fiancee will join the Queen for Christmas at Sandringham and attend the traditional church service is not just a benevolent gesture from monarch to a much-loved grandson.
Instead, it represents a sea change in the Victorian attitudes which for so long have coloured the royal approach to modern life. No such invitation was extended to Kate Middleton, nor to Camilla Parker Bowles — and certainly not to Lady Diana Spencer — before they married into the family, according to the Daily Mail.
But it is the manner in which Meghan is being fast-tracked into royal life long before her wedding that is so startling. For I can reveal that earlier this week the American actress had another unusual starring role — accompanying Harry and the Queen to the Royal Household Christmas party hosted by the Lord Chamberlain at Windsor Castle.
In a more intimate re-run of her first engagement, at Harry's side in Nottingham earlier this month, Meghan plunged into a sea of welcoming faces gathered in the castle's great reception rooms.
This time they were footmen, housemaids, butlers and pages, the domestic staff and gardeners who keep Buckingham Palace and the other royal residences ticking over. While the Queen, escorted by Prince Andrew and her cousins the Dukes of Gloucester and Kent, was greeted with affection, all eyes inevitably were on the smiling figure of Meghan.
Wearing a burgundy lacy cocktail dress, demurely cut just below the knee, she moved easily though the crowd of well-wishers just as she had a fortnight earlier, accepting congratulations from the men and women who in a few months' time will address her as "Your Royal Highness".
At the party, the formality was kept to a minimum with handshakes rather than curtsies. "She asked everyone she met their names and what they did,' one guest told me. 'It was very natural."
Just as he had in Nottingham, Harry showed his confidence in her by allowing her to work her part of the room alone.
As the 900 guests sipped flutes of Mumm champagne or Sandringham apple juice, Meghan, who didn't drink, circulated through the Waterloo Chamber, St George's Hall and the Grand Reception Room where her own wedding reception will be held next May. It took her more than an hour.
In fact, Meghan disclosed that she and Harry had spent last weekend at Windsor looking over the state rooms as they began making plans for the wedding. Clearly the benefit of being at Monday night's party was to experience what the same rooms are like when they are full of people.
Her presence was a surprise to staff, who laughed when the Lord Chamberlain, Earl Peel, said in his address with masterful understatement that next year would be a busy one. He didn't have to mention the royal wedding.
But it is the breath-taking speed with which the star of the TV show Suits is being absorbed into the royal world, while still not a royal, that has amazed even the most up-to-date courtiers.
Meghan and Harry announced their engagement on November 27, travelled to their first public outing on December 1, and will be seen in public with all the senior members of the Royal Family in 11 days' time when they attend the traditional Christmas Day service at St Mary Magdalene church on the Queen's estate in Norfolk.
It will be a testing time for Los Angeles-born Meghan. Christmas at Sandringham is a daunting prospect for an outsider, even one as poised as the 36-year-old Ms Markle.
Meghan's presence means that this Christmas will be a historic one. No unmarried partner has ever been permitted to sit around that polished long table in the green-walled dining room — hung with Spanish tapestries — for the family lunch.
Even though she, too, was newly engaged at Christmas 2010, Kate had to wait until the following year after her wedding to receive an invitation. She is now a veteran of six such Christmases and will be a valued guide for Meghan.
With more than 30 members of the family expected — the numbers are this high only every other year because of guests' commitments to other in-laws — Meghan's first task will be to try to remember all their names.
She will also need to know who the Queen's favourites are when it comes to the seating plan for lunch. Usually, it is Princess Anne's son Peter Phillips and the monarch's niece Lady Sarah Chatto who sit either side of the Queen. But yesterday some staff were speculating whether the Queen might place herself between Harry and Meghan.
"Who knows, everything seems to be up for grabs this year," says a courtier mischievously.
Certainly William, who has done so much himself to end royal froideur by insisting that his wife's family, the Middletons, are included in royal gatherings, will be excused if he feels a little envy at opportunities being extended to Harry and his fiancee.
And what about Prince Charles? For years, he had to suppress his great irritation that Camilla remained excluded from so many family get-togethers — until he made her his wife.
One thing that Meghan will be grateful to avoid is the scramble for the best bedrooms — en-suite dressing rooms are particularly prized. When Prince Edward and the Countess of Wessex celebrated their first Christmas there as a married couple, such was the pressure on space that they were given separate bedrooms. Instead of sleeping under the Queen's roof at Sandringham House, Meghan and Harry are expected to billet themselves with William and Kate at Anmer Hall, the Cambridges' country house a short drive away.
So what is in store for Meghan, and how will she bear up to all those royal eccentricities as she scatters some Hollywood glamour over this most traditional of gatherings?
The first thing she will have to get used to is that the royals follow the German custom of handing out presents on Christmas Eve. Few of the presents are extravagant.
"When you have everything, you have to have something you can use, something practical rather than decorative," says a servant who has witnessed these scenes. "The Queen likes things for picnics or for a barbecue, a rug perhaps. Once, she unwrapped a washing-up apron and was thrilled."
Typically, the candlelit black-tie dinner, served at 8.30pm, will be potted Norfolk shrimps, locally shot game or a lamb dish followed by tarte tartin with brandy creme or a souffle, all served on the finest china and silverware. The next morning, after Prince George and Princess Charlotte open their stockings, Meghan and Harry will be readying themselves for the crowds who will greet them outside church.
If the weather is fine, the younger royals will walk. Then comes Meghan's most critical moment — Christmas Day lunch. It's traditional fare of turkey with all the trimmings and is followed by not one but two flaming Christmas puddings. Guests sit down at 1.15pm prompt and it's all over in an hour.
By the time she and Harry leave, Meghan will also have packed in a post-prandial walk and, of course, watched the Queen's Christmas message on television along with everyone else. Whether the actress suggests the family sit down to watch a couple of episodes of Suits after the monarch's message remains to be seen.