The Duke of Sussex’s chief of staff has quit his role after just three months suggesting that Prince Harry and Meghan Markle’s US operation is crumbling.

Josh Kettler, their chief of staff, was once considered the perfect person to guide Harry "through the next phase".

"Josh Kettler is no longer working for them," a Californian source revealed to the Daily Mail, in a major blow shortly before the Sussexes are due to embark on their "quasi-royal" tour around Colombia.

Mr Kettler has joined the couple on other important tours this year, including supporting Prince Harry in London to celebrate the tenth anniversary of the Invictus Games, the sporting event he created for injured and sick service personnel.

Referring to his departure as "no surprise", royal expert Tom Quinn has discussed the "problem" that has likely led to Mr Kettler's exit - as well as the others that have joined and left their positions in recent years.

Speaking to the Mirror, he said: "In the years since Meghan and Harry married in 2018, they are estimated to have lost a staggering amount of key members of staff. One former employee told me the problem is that Meghan and Harry always assume that it is as easy to do something as it is to tell someone to do it. The couple hates being told something is just not possible."

Mr Kettler joins a long line of quitters, following the exit of Bennett Levine, manager of the Sussex's TV company Archewell Productions, who quit at the start of the year, as well as the Oscar-nominated producer Ben Browning, who quit as head of internal content at the company in January last year.

Despite Mr Quinn's comments, PEOPLE reported that he was "hired on a trial basis" and that they made the decision to part ways, with "both sides agreeing it wasn’t the right fit".

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The couple are said to have lost 18 members of staff since they married in 2018, with at least nine quitting since their move to the US.

Mr Quinn continued: "The real issue is that Kettler’s departure reminds everyone that working for Meghan and Harry is a seemingly impossible task. They are just too demanding and always expect too much. Which is why Meghan has failed to appoint a chief executive for her internet cookery and lifestyle brand."