Prince Charles secretly meets with Prince Harry and Meghan Markle

Things are not looking great for Prince Charles' relationship with his son, Prince Harry.

The Duke and Duchess of Sussex reportedly stopped in at Windsor Castle last week on their way to the Netherlands for the Invictus Games but a royal family expert has claimed Prince Charles was "reluctant" to privately meet with the couple.

The NY Post has reported that author and journalist Robert Jobson appeared on GB News last week where he told host, Dan Wootton: "Charles was not particularly happy about doing it as far as I was aware."

"They only agreed to do the meeting if nothing was said about him whatsoever on American TV."

"The Prince of Wales has reached the end of his tether, they haven't been in contact, and I think if he'd started blurting about that meeting, I think that would be the end of it for him and Harry."

He also claimed Prince Harry was late to the meeting, which has only added to Prince Charles' frustration toward his son.

Prince Harry's relationship with his family has become increasingly strained since his decision to resign from royal duties two years ago with fears things got worse after the Duke failed to attend his late grand-father, Prince Philip's memorial service at the end of March.

Days after the duke's meeting with his father, Prince Harry had an in-depth interview with US Today show host Hoda Kotb, where he admitted he "doesn't know" if he will be attending the Queen's Platinum Jubilee in June.

"I don't know [if we'll go] yet," he said. "There's lots of things ... Security issues and everything else. So this is what I'm trying to do, trying to make it possible that, you know, I can get my kids to meet her [the Queen]."

Prince Charles, Prince of Wales and Prince Harry, Duke of Sussex secretly met at Windsor Castle last week. Photo / Getty Images

The news comes amid the duke's recent legal proceedings against the UK Government and their refusal to let him personally pay for police protection when he and his family visit Britain.

The Sussexes lost tax-payer-funded police protection after stepping down as working royals before moving to the United States in 2020, claiming their decision was due to "unbearable intrusions and racist attitudes of the British media".