The book, titled Prince Philip Revealed, comes after what has been a tumultuous year for the Windsors.

In January, Harry and wife Meghan Markle announced that they would be stepping back as senior royals with a view to becoming financially independent.

In an extract from her book, published in the Mail on Sunday, Seward claims Philip felt the decision was a "dereliction of duty".

She writes: "As far as Philip was concerned, Harry and Meghan had everything going for them.

"A beautiful home, a healthy son, and a unique opportunity to make a global impact with their charity work."

Since stepping down and moving to the US, Harry and Meghan have said they want to maintain a role in public life and work to bring about positive change.

This week saw them confirm a deal to produce documentaries and other programmes for streaming giant Netflix thought to be worth around £112million.

The couple have said they want to use the platform to create "content that informs but also gives hope".

Prince Andrew's disastrous TV interview last year where he was grilled over his association with Epstein led to his own announcement that he would be stepping back from his royal duties.

Andrew is known to have stayed on multiple occasions at the homes of the paedo financier, who has been accused of subjecting dozens of women to sexual abuse over more than a decade.

At least one of Andrew's stays came after Epstein's conviction in 2008 for procuring an underage girl for prostitution.

One of Epstein's accusers has also alleged that she was forced to have sex with Andrew when she was only 17 years of age - a claim the prince denies.

Andrew has vehemently refuted any accusations of wrongdoing or knowledge of Epstein's crimes.

On the allegations, Seward writes: "Andrew allowed himself to be seduced by the rich and powerful whose only interest was his royal connection and the doors it could open.

"For Philip and the Queen, their son’s failure of judgment was a tragedy.

"Not only had he besmirched the reputation of the monarchy but had become involved in something extremely distasteful and far more serious."

Buckingham Palace as well as representatives for Prince Andrew and the Duke and Duchess of Sussex have been approached for comment.