EXCLUSIVE: Inside Prince William's Fight to Strip Estranged Brother Harry and Wife Meghan Markle of Royal Titles Once he Takes Throne From 'Dying' King Charles

Prince William is preparing to take drastic revenge on his rebel brother when he becomes king, with sources telling RadarOnline.com he will not tolerate his sibling and sister-in-law continuing to use royal titles "in any form."

"There is no way King William will stand for the continued use of the Sussex titles," a close friend said. "They will be stripped from them as he is determined to find a way."

Fresh controversy over Harry and Markle's continued use of their Sussex title kicked off in May after Markle, 43, was seen using her Her Royal Highness (HRH) title in a private note included with a gift basket shared in a video by her friend, IT Cosmetics founder Jamie Kern Lima.

This, alongside a message from Ukraine’s Deputy Prime Minister Yulia Svyrydenko addressing her as HRH in an Instagram post, sparked renewed scrutiny over why Meghan and Prince Harry, 40, still retain the HRH styles they agreed not to use publicly when they stepped back from royal duties in January 2020.

Under their agreement reached with Queen Elizabeth II at the time, the Duke and Duchess of Sussex were allowed to retain their HRH titles but were prohibited from using them for commercial purposes.

In a palace statement released in 2020, it was stated: "The Sussexes will not use their HRH titles as they are no longer working members of the Royal Family."

Markle's gift card, however, was sent in a private capacity and not as part of a commercial venture – meaning it did not violate the agreement, according to constitutional experts.

Nevertheless, sources close to William, 42, say the Prince of Wales has been angered by what he sees as a breach of royal decorum.

"William sees this as another kick in the teeth," one insider said – adding: "It may have not amounted to a formal breach, but he hates the way the couple are continuing to capitalize on a title given to them by a family they chose not to be a part of, and hates the way they act like royalty in America."

"It's made him determined to find a clause to strip them of their Sussex title when he takes over from King Charles – which will not be long.

"It's is part-revenge and partly his desire to totally overhaul the royal family and officially get rid of its bad apples like Harry.

"It's part of a real blueprint of change as he knows the public want an institution that serves them, not one that is obsessed by drama and feuds – all while getting paid by the taxpayer."

Despite Wiliiam's desires, the legal process for removing royal titles is not straightforward.

The HRH style could be more easily removed than the peerage titles of Duke and Duchess of Sussex, but even that would require the reigning monarch to act – likely through a formal letters patent or, more likely, with support from Parliament.

Craig Prescott, a constitutional law expert at Bangor University, explained the complications by saying: "Clearly when (Harry and Markle) stepped back from royal duties, one of the agreements was that they would not use these HRH titles, but they still retained them.

"That's because to strip them of their HRH titles is a little bit complex… they still have their HRH titles, and the formulation was that they would not use this in an official capacity so that commercial activities don't have a royal seal of approval."

Prescott added: "I think what is unusual about this is that it has come out in the open – and it's the blurring of the personal and the private.

"But this is a friend with whom she is doing a public appearance, so that’s really where the controversy lies."

A bill was introduced in Parliament in 2022 that could allow the monarch to remove titles more easily, but it has not advanced.