Harry and Meghan sue over 'drone photos' of son Archie

As well as discussing Meghan's relationship with Kate Middleton, and the Duchess of Sussex's treatment within the royal family, the book also details Prince William and Prince Harry's brotherly bond.

It paints the most intimate picture yet of how hard the Duchess of Sussex tried to fit into the royal family before she and Prince Harry ultimately made the decision to step back from their senior roles.

"I think he's so desperate to please her and go along with whatever she says, no matter how ill-conceived it is".

But despite how obviously popular the pair was, Harry reportedly grew frustrated that he and his new wife "took a back seat to other family members".

Worse still, there were only a handful of people working in the palace that they could trust. It claims that the young couple referred to the palace old guard as "the vipers".

The authors said that Harry and Meghan "liked being in control of their narrative" in the early days of their marriage.

But being told to operate under Buckingham Palace's umbrella after splitting their household from William and Kate's was "a big disappointment to them".

Meghan and Harry, according to Scobie and Durand, struggled to understand "why so few inside the palace were looking out for their interests", since they were so popular.

"The fact is you are attacked by public opinion and in the media and within the Royal Family you do not get the support".

The book also reveals Harry and Meghan whinged about their own projects being cast aside in favour of those being carried out by future monarchs higher up the royal food chain and were furious at courtiers who leaked stories about them to the press.

One royal expert quoted by BBC News said the couple had gone through a "nightmare" since moving to the United States, following their shock split from royal life earlier this year.

The Sussexes say they did not contribute to the book, but Scobie and Durand's account is based on extensive insight from friends of the couple.

"The couple recently learnt that someone is shopping photographs of their 14-month-old son, Archie, falsely claiming to have taken them on a "recent" public outing "in Malibu", the complaint, filed on Thursday for invasion of privacy, said.

The couple chose to live at least part-time in North America "to escape the incessant United Kingdom tabloid fabrications", the lawsuit says.

The couple's attorney, Mr Kump, said on the lawsuit: "Every individual and family member in California is guaranteed by law the right to privacy in their home. He is that besotted with her", she said.

It marks the latest example of the Sussexes actions against what they have previously described as "invasive" tabloid media.

The group claims that a grant of $145,000 was paid to Sussex Royal by the Royal Foundation, while another sum of $144,901 was allegedly paid by William and Catherine to Harry's non-charitable organisation Travalyst.