Meghan Markle makes surprise appearance at Queen's Christmas party

Queen Elizabeth had a special guest at her staff Christmas party at Windsor Castle on Monday — Meghan Markle! The American actress made a surprise appearance at Her Majesty’s annual soirée with her fiancé Prince Harry. According to HOLA!’s sister brand HELLO!, a source said, "Harry and Meghan spent about an hour at the party and they were really friendly and went around talking to everyone. Meghan was very sweet and so beautiful." The Suits alum looked festive for the occasion wearing a red dress.

Harry, 33, and the TV star, 36, are set to tie the knot in May at St. George’s Chapel, Windsor Castle. Meghan has been spending time at the royal residence, touring the rooms as she prepares for her wedding there.

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VIEW GALLERY Meghan attended Her Majesty's annual staff Christmas party on December 11 with Prince Harry Photo: Jeremy Selwyn - WPA Pool/Getty Images

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Next week, she and Harry will travel to Sandringham where they will celebrate Christmas with the royals. Harry’s bride-to-be is the first non-married partner to be invited to spend Christmas with the Queen and the rest of the royal family at Sandringham — a sign that she has been fully welcomed into the institution.

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At her first joint engagement with Prince Harry in Nottingham, Meghan told one well-wisher: "I'm so happy, I've been made so welcome." The brunette beauty also revealed that she has had tea with the Queen on a number of occasions and has bonded with her future sister-in-law Kate, who is "wonderful.”

VIEW GALLERY The Prince and American actress will tie the knot at Windsor Castle in May Photo: Jack Taylor/Getty Images

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Christmas for the royals is steeped in tradition — something Meghan will experience for the first time this year. The Queen and Prince Philip usually retreat to their country home, Sandringham Estate, the week before Christmas, around December 21, to prepare for the big family reunion. Other guests arrive at the 20,000-acre estate from December 23 in order of precedence, with Prince Charles and the Duchess of Cornwall usually the last to arrive.

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Presents are opened on Christmas Eve, followed by an afternoon tea and formal dinner, where the ladies don their finest gowns and jewelry and the men wear black tie. It is a relatively formal affair, but also the chance for the families to catch up. This year there will be plenty of exciting news to talk about; as well as Meghan and Harry's royal wedding in May, Prince William and Kate are also expecting their third child in April.