This is to ensure each guest has been "well fed", Seward claims.
According to Ingrid, the tradition dates back to King Edward VII's reign in the early 1900s.
As the festivities undeniably revolve around eating, the Royal Family first enjoy a turkey dinner with all the trimmings before indulging themselves in an afternoon tea complete with a "gargantuan iced cake".
The Queen's guests are also expected to "enter the dining room in order of seniority."
After they are then seated, "the head chef carves the turkey" and "paper hats are donned, but not by the Queen."
In order to "make room" for their lavish afternoon tea, the Royal Family then walk the grounds of the Sandringham estate and enjoy a "candlelit dinner in the dining room" in the evening.