Kate Middleton denied Queen Elizabeth II’s invitation to a Royal Family event.
The Princess of Wales, who was dating Prince William in 2006, refused the join the royals for Christmas at Sandringham.
Royal expert Robert Lacey reveals Kate at the time demanded a proposal from William, who still had his doubts about marriage.
He wrote: “By 2006, the couple had been dating seriously for the best part of five years. Yet when William invited Kate to join him that year at Sandringham for the Royal Family’s traditional Christmas lunch, she refused.
“It was the first time the Queen had extended such an invitation to an unregistered ‘girlfriend’, but Kate had her own take on that break with tradition.
“She would go to Sandringham on Christmas Day only when she was engaged and had a ring to prove it.”
The couple had hit a rough patch in their relationship at the time.
Expert Katie Nicholl wrote: “William had been having second thoughts and sat down with his father and his grandmother to have a frank discussion about his future with Kate.”