Prince Harry and Meghan Markle's decision to return to the UK has provoked a 'crisis for the monarchy', a royal expert said. The Duke and Duchess of Sussex are understood to be returning for an 'extended period' of time, with Archie, seven, and five-year-old Lilibet starting at a British school in September.The family will move into a non-royal residence and will not be working royals. King Charles was only informed by his son on Sunday of his plans to move back within the next two weeks. The Daily Mail also understands that no mention of the family's return was raised or discussed when Harry, Meghan and their children met with the King at Highgrove earlier this summer.This suggests that Charles may have been blindsided by their latest announcement.'It provokes a crisis for the monarchy because the monarchy's responses are often poor when they don't know what to expect, like when the Epstein files were released,' Richard Fitzwilliams told the Daily Mail.'With this, you certainly don't know what to expect. You never know what happens in the wildlife, all sorts of things may happen. It is utterly ruthless if he did tell the King of his plans to move on Sunday.'Mr Fitzwilliams added the decision was evidence the Sussexes' were a 'disastrous failure in the US', after relocating to California six years ago. It comes as: Prince Harry and Meghan Markle announced they are moving back to the UK this month, six months after leaving for the US.King Charles only found about their return to the UK on Sunday with the move not discussed with him when he met with Harry just weeks ago. Prince Harry and Meghan are said to have already lined up a property to live in that is not a royal residence. Some suggest the move indicates the couple's American dream failed amid a string of unsuccessful Hollywood dealsThe couple previously moved to North America in 2020 in a move dubbed 'Megxit' after the pair stepped back from their royal duties Prince Harry and Meghan Markle (pictured in April) are reportedly moving back to the United Kingdom - six years after leaving for the US The Duke and Duchess of Sussex (pictured in February) are said to be moving back to the United Kingdom before the end of the month Archie, seven, and Lilibet, five, are thought to have already enrolled in a British school (the family are pictured in December 2025)And suggested Harry, 41, feared how his brother, the Prince of Wales, would receive him and his family when, or should, William takes the throne. 'This is actually an extremely serious situation. What they have done is very clearly chosen King Charles's reign to do this knowing their options might be very limited when, and if, William becomes king,' the royal expert said.'I strongly suspect that William would look very closely at their titles and possibly the titles of their children. William will see this as total proof they couldn't be trusted for a single second.'Sources insist, however, it is not in the Sussexes' 'plan' to return to the royal fold. Fitzwilliams continued: 'The fact of the matter is this is absolutely sensational because it's one thing discussing what might happen, but when they are actually here and able to put on the charm, which is undoubtedly what they'll try and do, who knows what might happen.'They are still in line to the throne. Remember, that is still around. There would be a massive charm offensive. The British public can change their views, like they did with Camilla.' It is speculated the Sussexes had been planning the move back to the UK for a while, driven by Harry's lack of 'role' in the US. 'I don't believe Meghan wanted to come back, but Harry did. He had no role, it was quite literally doing pathetic cameo performances in Meghan's shows,' Mr Fitzwilliams added. 'They have failed in the United States. Meghan's career hasn't taken off at all'However, he suggested the Sussexes' 'brand' makes it difficult to predict whether the British public will choose to embrace or reject the couple when they return. King Charles is understood to have found out about his son's impending move back to Britain on Sunday (the pair are seen together in 2022) Meghan and Harry (pictured with Lilibet in April) are set to keep hold of their £11million mansion in California 'The facts are that they have a brand that everyone knows who they are. When they do and say things, they get publicity, and from that point of view, you never know what happens when they're actually here. And they're going to be here a lot,' Mr Fitzwilliams said.'What will happen? It won't make life easy for William and Catherine and their family, and how they were hoping the monarchy would progress.'The royal expert added the strength of the Sussex 'brand', and this sudden drop of news they are relocating, 'knocked [the publicity around]' Queen Camilla's 'moving' account of the pressures of keeping King Charles's cancer diagnosis secret during the early stages. 'The Sussexes don't care about that,' he said. 'It has clearly been a very problematic and stressful time. William called it absolute hell. He said it was brutal to have two senior members of the royal family suffering from cancer.' Harry was already scheduled to visit Britain to attend a WellChild Awards bash next month and was set to stay in a room at Buckingham Palace.But the Duke and Duchess, 45, no longer require accommodation for their patronages with the whole family believed to be returning for an extended period within the next two weeks.Archie and Lilibet have already enrolled at a school – and the family are reportedly planning on staying until the children finish education.It is not yet known, however, whether the move will be a permanent one. The location of Harry and Meghan's new home has not been revealed for privacy reasons. It is not yet known where Harry and Meghan will be living when they move later this month (The Duke and Duchess are seen with Princess Kate and Prince William in 2022) William, Charles and Harry are pictured at the procession for the Lying-in-State of Queen Elizabeth in 2022The couple are set to keep their £11million home in Montecito, California, where they have lived since moving across the Atlantic Ocean. They also still own a residence in Portugal.The surprise news comes six years after the couple left Britons in disbelief when they stepped down as working royals.In a statement released at the time, following a 12-month review, Elizabeth II confirmed that they would not 'continue with the responsibilities and duties that come with a life of public service'.The former monarch added that Harry and Meghan would not be maintaining a 'half-in, half-out' approach to their duties. Harry was later stripped of his honorary military titles.It came after the pair, who wed in 2018, announced their decision to leave without consulting Charles, Camilla or Prince William – in a move which sparked fierce criticism.The Duke and Duchess were accused of 'press[ing] the nuclear button' when they made the bombshell announcement just days after returning from a six-week break in Canada. They later permanently moved to California in March 2020.It was claimed earlier this year that Palace staff had given Meghan the nickname 'Duchess Difficult' during her time living in Britain.The American was accused of bullying and, on certain occasions, even making staff cry.It was said that workers were left 'in a psychologically delicate state' and 'viewed her capacity for revenge as infinite', an expert has alleged.Meghan vehemently denied the allegations. She described the release of such accusations as an orchestrated smear campaign against her.Veteran royal correspondent Valentine Low first broke the bullying story in March 2021, just before Harry and Meghan were to appear on screen with Oprah Winfrey to discuss Megxit.He said: 'There had been one or two stories which suggested there were difficult relations between Meghan and her staff. We'd seen them and the phrase 'Duchess Difficult' had been used. Sources, however, suggest that King Charles 'welcomes' the opportunity to see more of his family (Harry, Meghan, Charles and Camilla are seen together in 2022)'We knew Meghan was angry about those stories. We knew she challenged that narrative'.He claimed that some of the royal staff who had worked with the Sussexes were still in a 'very fragile state' more than two years later – and despite the royal couple having emigrated 5,000 miles away to the US.'They were very worried about what Meghan would do to them. They viewed her capacity for revenge as infinite.'They'd left the employ of the Royal Family and they still were in a psychologically delicate state as a result of what happened to them at that time.'The couple famously appeared in public together for the first time at the Toronto Invictus Games in 2017 when they were pictured hand-in-hand at a wheelchair tennis event.The Duke and Duchess of Sussex later moved to Vancouver Island in 2020 after quitting the Royal Family in what became known as 'Megxit'.Harry's relationship with both his father and brother, Prince William – the future monarch – is since believed to have become strained.The siblings are not thought to have spoken for years, with William and his wife Kate Middleton understood to have been 'deeply hurt' by allegations made in Harry's memoir, Spare.The brothers were said to have promised to put aside their differences in honour of their late mother Princess Diana – but, according to royal author Phil Dampier, that promise has been broken.He told the Mail: 'William and Harry put aside their differences for the unveiling of the statue of their mother Princess Diana [five years ago], but things are much worse now.'I think William would find it very hard to meet Harry, even to honour Diana's memory. Next year marks the 30th anniversary of her death, so that would be an obvious time for them to try and heal their rift and at least be seen together, but I don't think William's heart is in it.'Friends tell me that, as far as he is concerned, Harry is the past, and he is only concerned about the future for his wife Catherine and their children George, Charlotte and Louis.'He will never forgive Harry, in my opinion, not just for leaving the Royal Family, but for the dirt he dished out in his book Spare, the Netflix show and the Oprah Winfrey interview.'It led to Catherine being smeared as a racist, and he will never forget that.'Harry is reported to have long missed living in the UK – and it has even been speculated that he has been 'desperate' for Archie and Lilibet to experience life in his home-country.Harry hopes that Charles will open next summer's Invictus Games alongside him next summer in what would be a major move towards reconciling their relationship. It is, nevertheless, currently unknown whether that will materialise.Harry and Charles enjoyed a private reunion, along with Meghan and their children, last month – four years after the monarch last saw Lilibet and Archie.The Duke and Duchess were welcomed by Charles and Camilla to the King's private residence, Highgrove House in Gloucestershire, in a move which marked a step towards healing Harry's relationship with his father.Charles, as well as Camilla, had also been subject to criticism from the 41-year-old in his 2023 memoir – but Harry visited the King a year later amid news of his cancer diagnosis.The Sussexes already set about rebuilding a base in Europe prior to recent revelations, having bought a property in Portugal at the plush Costa Terra resort in Melides in 2023.The couple and their children holidayed at the resort only a month ago as Meghan shared snaps of pristine beaches, swimming pools and restaurants to her Instagram.The Sussexes have been contacted for comment.