The REAL reason Kate Middleton politely declined the Queen's unprecedented invitation to spend Christmas at Sandringham with the royal family

Every year the Royal Family travels to Sandringham to celebrate Christmas, where they have a number of famous traditions - from the gift giving to the annual 'weigh in' after the feast. But in 2006, the late Queen made the unprecedented move of inviting an 'unregistered' girlfriend for the first time - Prince William's partner Kate Middleton. In 2006, the late Queen made the unprecedented move of inviting an 'unregistered' girlfriend for the first time - Kate Middleton, pictured on December 1 of that year The Queen, pictured at the 2006 Christmas Day service, usually only invited royal couples to Sandringham once they got married Every year the Royal Family travels to Sandringham to celebrate Christmas, where they have a number of famous traditions - from the gift giving to the annual 'weigh in' after the feast Christmas at Sandringham is run like a military operation with everything timetabled, from the guests' arrival, to eating breakfast, walking the dogs, sitting down to lunch and retiring to bed. Pictured at an old boys match at Eton College on March 18, 2006 Harry's girlfriend at the time Chelsy Davy and Kate Middleton watch their boyfriends play in a charity polo match at the Beaufort Polo Club on July 29 Kate was among the crowd watching William at his passing out parade at Sandhurst on December 15 Queen Elizabeth II passes her grandson Prince William, as she inspects graduates during a passing out parade at the Royal Military Academy Sandhurst on December 15, 2006 Kate Middleton, with her parents Carole and Michael, at the Sovereign's Parade at Sandhurst Military Academy for the passing-out parade of her boyfriend Prince William Although Kate was an established girlfriend at that stage, she still chose not to come to Sandringham Prince William arrives at church for the traditional Christmas Day service in Sandringham in 2006 Princesses Beatrice and Eugenie, daughters of Prince Andrew, arrive at St Mary Magdalene church on the Sandringham estate on December 25, 2006 Queen Elizabeth II smiles at her great niece, four-year-old Margarita Armstrong-Jones in 2006 Princess Diana was not invited in 1980, two months before her engagement to Charles was announced. Queen Elizabeth II is presented with flowers from young children after attending the traditional Christmas Day church service in 2006 After Kate turned the invitation down, the lovesick Prince William seemingly kept in touch with her by mobile phone while out hunting Instead of spending Christmas at the world-famous Sandringham Estate, Kate chose to travel to Scotland to spend the holiday with her parents and family.