While he’ll likely be the center of attention as the Royal Family gathers next week to celebrate his first Christmas at the Queen’s country retreat, Sandringham, Prince George will actually find himself quietly ensconced in the nursery when the real holiday action takes place.

For weeks now, upwards of 100 staff members have been preparing a days-long sumptuous house party for George’s parents the Duke and Duchess of Cambridge and the extended family.

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Darren McGrady, who worked for the Windsors for 15 years – the last four of which, until 1997, in the employ of Princess Diana and her young sons – says nothing much will have changed from his days behind the carving station and in the kitchens.

The festivities begin on Christmas Eve, by which time the guests will have arrived through the front door, as all “packages and parcels would come to the back and be brought through the kitchen,” says McGrady, author of Eating Royally.

Prince Charles might also bring his own supplies. “He would always come with a hamper full of organic food. He liked his poached plums from Highgrove. His valet would come into the kitchen with three or four bottles of plums to be kept in the ‘fridge,” remembers McGrady.

At around 4 p.m. guests enter the white Drawing Room for tea. The next stop is the red Drawing Room, where the staff has already laid out the presents on trestle tables for each family member.

What do you get those who have practically everything? Novelties and gimmicks.

“The crazier and the more quirky is what they love. It’s not about something really amazing or a Cartier watch,” McGrady says. Young William once received a Winnie the Pooh-themed china set.

“Diana got upset once because she bought cashmere sweaters and she thought that would be nice, but they don’t do that. Prince Philip would get a peppermill with a light on it and he would think that was hilarious.”

After the gift swap comes time for the first major change of outfit for Kate and the other guests prior to the meal. Normally, at 8:30 p.m., this involves “something festive, some game, like pheasant or venison, and roasted wintery vegetables, like parsnips.”

Breakfast on Christmas morning is a full-on fry up for the men – bacon and sausage, kippers and kidneys, juices and cereals. The women will normally have fruit and perhaps a boiled egg taken to their rooms on trays.

Often, McGrady recalls, the royals bring their own china. “I had to make sure it went on the right plate. The Queen Mum’s was a pattern she had at home and she wanted it for her breakfast. They like the continuity.”

The church service follows at St. Mary Magdalene. On her first Christmas as a member of royal family, in 2011, Kate (with William) joined the Queen for a morning service at 9 and then again at 11, when the entire family parades to the church.

The head chef, accompanied by some of his team, carve the first of two 25-lb. turkeys at the buffet in the dining room, with the Queen first in line. “At the end of the carving, it’s the one time of the year that she would give the head chef a drink, and he will toast [the family] with ‘Happy Christmas.’ ”

There is also a buffet of foie gras, boar’s head, venison and salmon trout. “Once everyone has sat down with their meat, the butlers will come around with their Brussels sprouts with fresh roasted chestnuts and roast potatoes.”

Dessert is two Christmas puddings and brandy sauce, mince pies and hard butter.

The dining room table seats 22, just enough space for the adults and older children. Anyone younger remains in the nursery, “until,” notes McGrady, “they can hold conversation and hold knives and forks correctly.”

After lunch the family will watch the Queen’s annual address to the nation, which airs at 3 p.m. U.K. time, before adjourning either to the Saloon, where the Queen’s favorite jigsaw puzzles are laid out, or else to exercise on the 20,000-acre estate.

“I think they liked to get away from each other,” as Sandringham is much smaller than Windsor Castle, McGrady says. “We would have two hours between 3 and 5, and we’d go out for a walk and we might bump into Princess Diana during our walk.”

In the evening a cold buffet is held in the Dining Room. “All the food from lunch goes back out for the buffet. And there will be mixed salads and hot new potatoes. And they have the [sweet] mince pies and put the brandy butter inside.”

The following morning, after a big breakfast to mark the British holiday of Boxing Day, the men go shooting. Kate and the women might also go, or at least for lunch.

That evening’s three-course dinner might kick off with Gleneagles pate or a fish course, followed by tenderloin steaks with a whisky mushroom cream sauce. Dessert might be bread-and-butter pudding or a trifle.

“We would also do a big silver tray of sliced meat from the Christmas buffet menu – venison, or some fish,” says McGrady.

Guests generally start to head off on Dec. 27, with Kate and William likely to visit her family, while Sandringham is prepared for the next round of the Queen’s relatives and friends, who come to stay for New Year’s.

For more on the royals’ Christmas, pick up PEOPLE’s special double issue, featuring the best and worst of 2013, on newsstands Friday.