Prince Harry and Prince William must end their feud now – or the UK will face “incalculable damage,” a royal expert claims.

Meghan Markle and Prince Harry will “seethe and seek revenge” if William, heir to the throne, refuses to make peace with his brother, according to newspaper columnist Andrew Norman Wilson. He argues this would lead to great tensions when William, Prince of Wales, becomes king.

“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,” writes Mr Wilson.

“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.

“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?”

Pictured in 2010 in Gaborone, Botswana, Princes Harry and William had a strong bond

But Harry and Meghan, the Duke and Duchess of Sussex, sensationally quit royal duties in 2020 for a new life in California. They’ve since carried out TV work – with a large deal with Netflix – and Harry has released his controvesial memoirs Spare.

It’s Spare, though, that fuelled the tensions between Harry and William. With TV work seemingly drying up in the US, critics have suggested Prince Harry may need to overcome – or ease – the tensions to return to The Firm instead. Hints, including Harry and Meghan’s decision to include the titles HRH (His/Her Royal Highness) as well as the surname Sussex on passport applications for little Archie and Lillibet, have emerged recently.

“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.”

Mr Wilson’s opinion column comes as it is understood Duke of Sussex wishes to avoid “ambushing” the royals in a bid to maintain regular communication with his cancer-battling father. The olive branch came as senior staff for the King’s estranged son spoke with a palace official of a wish for a “roadmap for more regular communication” with his family.