Prince Harry and Prince William must end their family feud or the UK will face “incalculable damage”, a royal expert has claimed. The Sussexes will “seethe and seek revenge” if William, the heir to the throne, refuses to make peace with his brother, according to newspaper columnist Andrew Norman Wilson.

As reported in the Daily Mail, Mr Wilson writes: “When Charles vacates the stage, as one day he must, and William is anointed, a middle-aged brother in exile, on non-speakers with the sovereign but with a potential audience of billions, could do incalculable damage.”

He further warned: “It would be miles better [than Harry writing another book, for instance], then, that the Sussexes be brought in from the cold. Both sides should be seeking, not only diplomatic and political help, but personal counsel.”

The royal expert, however, also understood the hardship faced by Prince Harry growing up. He explains: “This was a pair of brothers who, from earliest childhood, were facing the broken marriage of their parents; their mother’s untimely death; unfounded and scurrilous speculation about Harry’s paternity; and generally a gnawing inferiority complex on Harry’s part – some of it understandable. Who wouldn’t feel inferior, after all, to the heir to throne?”

The Duke and Duchess of Sussex stepped down as working royals in 2020 to pursue a more financially independent life, and eventually settled in Montecito, California, with their two children, Prince Archie, six, and Princess Lilibet, four.

Since their departure, they have sat down in a tell-all interview with Oprah Winfrey, aired a Netflix docuseries titled ‘Harry & Meghan’ and Harry also released a controversial memoir, Spare, depicting his gripes with the Royal Family.

Mr Wilson also issued another warning about the future of the monarchy: “All those who have William’s best interests at heart – and this must include everyone who wants a bright future for the monarchy – must be begging him to extend some kind of olive branch to his wayward, disloyal and maddening younger sibling.

“If Harry and his father find a way to be reconciled, that would be a fine thing. But it is the next reign – that of William V – that is likely to be longer and of far more consequence.

“It’s no exaggeration to say that this row could one day begin the process that leads to a republic. And that could come much sooner than we royalists might like to admit.”