Earlier this year, Prince William refused to attend a lunch with his grandmother, Queen Elizabeth II, and his younger brother Prince Harry to clear the air and heal the alleged rift within the British royal family.

The claim was made by royal biographer Robert Lacey, who is also the official consultant on Netflix’s “The Crown.” The British historian, 76, is releasing a new book titled “Battle of Brothers: William and Harry - The Inside Story of a Family in Tumult,” which addresses the ongoing woes impacted by the royal family.

The book will also put the two brothers’ relationship into a historical context, exploring how the “heir” and the “spare” have impacted the British monarchy over the years. It features numerous interviews with palace insiders.

During a recent appearance on True Royalty TV’s weekly program “The Royal Beat,” Lacey claimed that things were so bad between the brothers following Harry stepping back as a senior royal with his wife Meghan Markle – or "Megxit" – that William turned down a lunch invitation from the queen to avoid spending extra time with the Sussexes.

“It infuriated William to the extent that when the queen said, ‘Alright, let’s have a meeting to talk about all this. Beforehand we will have a family lunch to talk things over, William actually said, ‘No, I do not want to come to the lunch. I will come and negotiate the over the table,’” Lacey claimed in a clip sent to Fox News on Monday.

“But he would not sit down at the family lunch with Harry.” Lacey alleged.

Lacey said that if William is ultimately given the role of the Head of the Royal Marines, “that will mark the rift.”

“I think that they have kept that position open for [Harry] if he wants to come back into the family,” Lacey explained. “If they are going to give it to William, I think that is the end of [the relationship between the boys].”

Rumors of an alleged royal feud came to light in 2019, when British bestselling author Katie Nicholl claimed that since Markle, 39 and Harry, 36 announced their engagement in 2017, William, 38, grew increasingly worried for his brother and his whirlwind romance with the American actress.

“William was quite concerned that the relationship had moved so quickly,” Nicholl claimed in the TLC documentary “Kate V. Meghan: Princesses at War?”. “And being close to Harry, you know, probably the only person close enough to say to Harry, ‘This seems to be moving quickly. Are you sure?’ And I think what was meant as well intended brotherly advice just riled Harry.”

“Harry is hugely protective of Meghan,” Nicholl continued. “He saw that as criticism, he interpreted that as his brother not really being behind this marriage, this union. And I don’t think things have been quite right ever since.”

Lacey said William had every right to be cautious.

“Meghan is a self-made woman,” he said. “She becomes a star, she becomes a self-made millionaire. I think that when William sat down with Harry and said there could be problems, I think events have proven him right.”

“I think that [Meghan] has come to realize how [some of her] speeches risk her husband’s relationship with the family and perhaps she may pedal back on some of these more extreme positions,” said Lacey.

The U.K.’s Evening Standard noted that in recent weeks, the Duke and Duchess of Sussex have been accused of interfering in the U.S. presidential election by urging Americans to vote.

Traditionally, the British royals don’t vote in elections, and “The Queen has to remain strictly neutral with respect to political matters," according to the monarch’s website. However, according to People magazine, there is no law forbidding it.

Lacey told “The Royal Beat” that he found Harry and the former “Suits” star “too preachy” and claimed William does more for some progressive causes than his brother and sister-in-law.

“People have said the Windsors don’t do ‘woke,’” he explained. “They don’t know how to handle progressive causes. However, I think William does it rather well. He does it better than Meghan and Harry.”

After notoriously stepping down as senior members of the British royal family at the start of the year and moving to North America, the Sussexes have recently settled down in Santa Barbara, Calif., after stints of living in Los Angeles and Vancouver, Canada.

A rep for the couple confirmed to Fox News that they purchased a home in the coastal city.

"The Duke and Duchess of Sussex moved into their family home in July of this year," a spokesperson said. "They have settled into the quiet privacy of their community since their arrival and hope that this will be respected for their neighbors, as well as them as a family."

A source told Page Six, who first reported the news, that the Duke and Duchess of Sussex hope this is where their son, Archie, 1, can grow up and lead "as normal a life as possible.”

Previously, Harry hinted at an alleged rift with his older brother in last year’s ITV documentary “Harry & Meghan: An African Journey.”

“Part of this role and part of this job, this family, being under the pressure that it’s under, inevitably stuff happens,” he said at the time. “But look, we’re brothers, we’ll always be brothers. We’re certainly on different paths at the moment but I’ll always be there for him and I know he’ll always be there for me.”