Prince Harry and Meghan Markle are an "act" and "live off publicity," historian Simon Heffer has claimed.
The Duke and Duchess of Sussex stepped down as working members of the Royal Family in 2020 and moved to the US via a short stay in Canada.
They later launched attacks on senior members of the Royal Family including Queen Camilla, Prince William and the Princess of Wales in the form of interviews and Harry's memoir Spare.
Speaking to GB News, Heffer said: "Harry appears to have bad relations with his brother and sister-in-law, given that his sister-in-law is probably the closest that we've got to a saint in the Royal Family at the moment, that's not very good PR on his part.
Harry and William were close growing up GETTY "His brother had a very difficult time, his wife has been ill and his father has been ill. The Prince of Wales has held the line pretty well.
"I think people are aware that Harry has not been supportive, it's one thing for him to go away and keep quiet, which is what the Duke of Windsor did.
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"It's another thing to go away and cause ructions, to give interviews, to make public appearances, to get into the press a lot.
"I mean, he and his wife clearly live off publicity. They are a brand. They are an act. And like all brands and all acts, they need the oxygen of publicity.
"That's what he's seeking now. That will always make things difficult for the rest of the Royal Family if that is his attitude to life, and it does appear to be."
He explained: "I understand he's got to earn a living, But nobody forced him into this. He didn't have to leave the Royal Family.
Simon Heffer labelled the couple an act
GB News
"It was quite clear, that his father in particular, wanted him to stay. It was quite clear that there was a serious job for him to do.
"He was very popular with the public.
"Since he got married six years ago, something has happened.
Meghan and Harry stepped back from royal life
PA"I'm not party to his private thoughts. I don't know anything about the internal workings of his marriage, but something has happened that has poisoned him, it seems, against his family and against the idea of royalty now."
Harry and Meghan have focused a lot of their efforts since stepping back from royal life on charity work through their Archewell Foundation.
The Duke of Sussex has also continued to spearhead the Invictus Games, which he established.