It is customary for royals to travel to Norfolk Ranch for Christmas, and on one occasion in 2006, Prince William invited his then-girlfriend Kate Middleton, who refused. The claim provided royal author Robert Lacey, whose upcoming book Battle of Brothers provides insight into the lives of Prince William and Prince Harry. Excerpts from the book were disclosed to the Daily Mail ahead of its October 15 release.

In it, Lacey said William and Kate had been in a relationship for about five years at the time the Duke invited her to the royal legacy.

But when William invited Kate to join him that year in Sandringham for the traditional Christmas lunch for the royal family, she refused.

The invitation was issued by the queen herself. This was unprecedented, Lacey adds, describing it as “the first time that the Queen made such an invitation to an unregistered” girlfriend “.

However, Kate appeared to be turned down on the grounds that she and William are yet to be married.

“She was only going to Sandringham on Christmas Day when she was engaged and she had a ring to prove it,” adds the royal writer.

The decision to break tradition came before William and Kate temporarily split in 2007, although Lacey has not explicitly mentioned why this is in excerpts from the book that has been released to the press so far.

READ: Kate makes an urgent visit to college students as thousands trapped in the chaos of COVID [INSIGHT]

Friends of the prince revealed during that time: “William has not stopped pining for Kate since their separation.”

“He kept saying she was an amazing girl and the best thing that happened to him.”

The author also reveals that the Duke misses Kate’s parents, Carol and Michael, and describes them as “calm and loving.”

Lacey said it was a “little wonder” William and Kate were seen dancing at a party in Dorset less than three months after they separated.

Prince William and Kate Middleton eventually got engaged in 2010 when he was 28 years old.

The two were on a safari vacation in Kenya at the time. The Duke apparently planned this ahead of time, offering an engagement ring that was formerly owned by the late Princess Diana.

The ring is studded with diamonds and sapphires. Prince Harry, William’s brother, had previously given his approval.

William and Kate got married in April 2011 at a ceremony in Westminster Abbey, London.

Other sections of the book reveal insights into the relationship between William and Harry, as well as details of the alleged temperament of the Duke of Cambridge.