The Sussexes are also said to be focusing on their separate projects, with Meghan particularly committed to promoting her lifestyle brand, As Ever. Harry and Meghan last visited Australia in 2018, when they were still senior working members of the Royal Family.

Now, Tom Bower, author of the upcoming book about the Sussexes titled Betrayal: Power, Deceit and the Fight for the Future of the Royal Family, has taken aim at the couple and the Duchess in particular, accusing her of “breaking” the late Queen Elizabeth’s promise.

Harry and Meghan still retain their royal titles despite quitting the Firm but during talks about their bombshell exit in 2020, it was mutually agreed that they would not be using their titles or royal links for commercial gain.

However, Mr Bower thinks Meghan’s latest ambition for Australia contradicts that promise.

He told Australian outlet The Daily Telegraph Sydney: “First of all, Meghan is doing it for money, it’s rather grubby. She’s monetising her royalty, which I think is pretty shabby because she promised the Queen she wouldn’t do that.

“I think they are going to find it much rougher than they anticipated when they arranged this trip. This trip to Australia is clearly to make money to raise their profile.”

One of the events Meghan is due to attend is a women-only gathering in Sydney, where tickets cost £1,440 per person and she will take part in an on-stage interview. Announced earlier this month, the Her Best Life Retreat will welcome up to 300 women for a three-day luxury event from April 17 to 19 at the five-star InterContinental Hotel.

The former Suits actress is set to appear as a guest speaker, with the programme including a gala dinner featuring an in-person conversation with Meghan, as well as “powerful conversations, relaxation, laughter and unforgettable experiences”, according to organisers.

Meanwhile, Harry will appear at a “workplace mental health summit” to explore the “need for urgent action to change attitudes”.

He will also reportedly focus on his Invictus Games charity and spend time with the Australian Defence Force.

It is understood that Prince Archie and Princess Lilibet will not accompany them on the trip.