Prince Harry and Meghan Markle have been warned that “only one thing” about them is keeping people interested as the couple have taken a significant hit to their popularity since quitting the Royal Family.

Royal expert Richard Fitzwilliams has claimed that one reason for this dip is the couple’s “monetising” of their royal connections, even as they spoke out about their negative experiences as part of the Firm.

He added that their decision to trash the royals through their Netflix TV series and Harry’s memoir Spare was “destructive” and they should have been more “publicity conscious” from the beginning.

The expert pointed out that the only reason they remain of interest is due to their connections to the Royal Family.

He told The Sun: “I think that people’s eyes have been open to the fact that they exploit the connection they have with the Crown and yet they also attack the Monarchy. If they weren’t royals, I don’t think there would be any specific interest in them.”

Mr Fitzwilliams explained that Meghan’s lack of popularity is likely the reason why she has chosen not to accompany her husband when he comes back to London this week.

The Duke of Sussex is attending a service at St Paul’s Cathedral on Wednesday celebrating ten years of the Invictus Games, but it will be a brief solo trip.

The commentator said: “Harry is very wise not to bring Meghan to the Invictus Games’ anniversary because it just simply wouldn’t work.

“But is the way that Meghan and Harry and the Royal Family have parted company and done so with so many public appearances that have caused problems.

“I don’t think that the Royal Family is particularly concerned with Harry and Meghan’s popularity.”

It is expected that Harry will reunite with his father King Charles while he is in the UK, although the Duke is likey to be staying at a hotel rather than a royal residence.

The Invictus Games event clashes with the first Buckingham Palace garden party of the season, but it is hoped the King will still be able to fit his son into his schedule.

But Prince William may be less keen to see his younger brother, especially after he and wife Princess Kate came in for a battering in Spare.

An insider told the Daily Beast: “Both sides understand each other’s position clearly. William and Catherine felt completely betrayed by Harry’s memoir. They don’t speak to Harry and Meghan, and they are certainly not about to start when Catherine is at her most vulnerable.”

Another source told The Mirror: “Their relationship remains extremely fractured. Harry has privately expressed a wish to sit down with his brother but now is not the time.”