Harry and Meghan leave their joint charity foundation with William and Kate

The "Fab Four" are going their separate ways. Photo / Getty

Prince Harry and Megan Markle have decided to leave the joint charity foundation they ran with Prince William and Kate Middleton.

In the latest development of the royal split of the "fab four", Harry and Megan "won't slot in line" or be "controlled" by William, a royal expert has told the Sun Online.

Royal commentator Duncan Larcombe said the move demonstrates that Meghan, 37, and Prince Harry, 34, intend to "do things their own way".

"It does seem odd. Why separate when you are both backing the same causes? Whether this is a sign of a rift, this is certainly a sign of a division," Larcombe told Fabulous Digital.

"It is clear that Meghan and Harry were initially prepared to slot in under the wing of William and Kate but that's not how they feel a year on."

The young royal group were named the "fab four" after appearing together on stage for their charity's first Q&A forum in the spring of 2018.

It has only been months after their first, and only, group public appearance that the group will go their own way and pursue their charities separately reports The Sun.

Prince Harry, Meghan Markle, Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge attend the first annual Royal Foundation Forum in 2018. Photo / Getty

The split from William and Kate could be a colossal blow for the Royal Foundation, which Meghan only joined after her wedding in May 2018, The Sun reported.

"Harry is going to forge his own path with Meghan. For years, before he met Meghan, he was the royal, third wheel, standing behind William and Kate," Larcombe added.

"He's now a fulltime working royal with his wife, he wants autonomy as to what he does, how he does it and how she does it, which is a definite change to how it was 12 months ago."

A palace insider told the Sunday Times "William's quite controlling, and he was in control when it was just the three of them, but now he's not".

They added that Meghan "knows all the tricks" and is helping Harry to max their "standable brand" and "William's going to have to get used to it".

Harry and Meghan are leaving the joint charity foundation they ran with William and Kate. Photo / Getty

Larcombe confirmed the insider's comments revealing "Meghan and Harry aren't going to be controlled by William. They are going to do it their way, and there is scope for them to do that".

William and Harry created the foundation together to promote their charitable ambitions. Kate and Meghan joined the foundation as patrons after marrying into the royal family in 2011 and 2018.