A royal expert has warned Prince Harry and Meghan Markle that they could only face humiliation and attract trouble with their return to the U.K. in September.

A spokesperson for the Duke and Duchess of Sussex said they will visit "charities close to their hearts" with their return to the country. But Richard Fitzwilliams suggested that their trip could be "fairly difficult" for them because their popularity among the British public has declined.

He acknowledged that their visit could be seen as "royal work" and is in line with their wish to "step back, not step down" from their royal duties. But he said that it would be like "stepping into a lion's den."

The royal commentator pointed out that Prince Harry and Meghan Markle have only tarnished their reputation with the public since Megxit in 2020. He told Newsweek, "We've had Oprah—we know how damaging that was and there have been a large number of interviews that they have given about the royal family, to say nothing of Harry's upcoming memoir."

He continued, "What has happened during this period is that their ratings have dropped phenomenally. Their popularity has plunged in Britain. They know when they appear that they are at war with the press here, it's rather like venturing into the lion's den now because you've got the public who are not supportive and you've got the press who are ferociously against them—and then you've also got the royal family where there's a rift."

The Duke and Duchess of Sussex will arrive in the U.K. on Sept. 5. They will attend the One Young World Summit in Manchester where the former "Suits" star will give a speech. Then on Sept. 6, they will fly to Germany for an event to celebrate The Invictus Games 2023. They will fly back to London on Sept. 8 where they will attend the WellChild Awards where the Duke of Sussex is a patron.

It will be the first set of public engagements for Prince Harry and Meghan Markle in the U.K. since they attended the Platinum Jubilee celebrations in June.

Prince Harry and Meghan Markle
The Duke and Duchess of Sussex Prince Harry and Meghan Markle at the Thanksgiving Service at St. Paul's Cathedral on June 3. Photo: Karwai Tang/WireImage Karwai Tang/WireImage