Lacey revealed the now-Princess of Wales received an official invitation to join the Royal Family‘s Christmas celebrations at their country residence Sandringham in 2006.
Traditionally, only those who are married to members of the family are invited to attend the gathering but the author suggested Kate got a nod as she was William’s long-term girlfriend by then.
But he argued she rejected the invitation as she wanted to wait until William officially proposed to her.
Kate Middleton had been William’s girlfriend for five years by the time she was invited (Image: GETTY)
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.”
However, commentator Katie Nicholl noted that the Christmas holidays in 2006 marked the beginning of a rough patch for the royal couple.
She claimed the pair had made plans to spend time together but William ultimately changed his mind.
Kate made her Sandringham debut eight months after her marriage to William in 2011 (Image: GETTY)
Kate has been a regular feature at Sandringham most Christmases (Image: GETTY)
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.”
Less than six months later, reports started to emerge suggesting William and Kate had called it quits – with the Princess of Wales later admitting that while she was unhappy with the decision “it made me a stronger person.”
Kate made her Sandringham debut at Christmas in 2011, eight months after the then-Duke and Duchess of Cambridge tied the knot.
The newly minted royal quickly joined in with Royal Family tradition and presented the late Queen with a jar of homemade chutney.
The custom of inviting only official spouses came to an end in 2017 when Meghan Markle joined Prince Harry at Sandringham on her first Christmas in the UK.
