The Duchess of Sussex faces being quizzed in court over intimate details revealed in a tell-all biography after the authors admitted that she was a source.
Finding Freedom, published yesterday, lays bare the innermost thoughts of the Duke and Duchess and the tensions behind the scenes that led up to their departure from official royal life.
It includes the claim that the Prince of Wales' 70th birthday photograph, which seems to show a happy picture of family unity, was an "absolute nightmare" to plan because his sons blew "hot and cold" with their father.
The 350-page book is expected to be thrust to the heart of a High Court privacy case brought by the Duchess against The Mail on Sunday.
The Sussexes have distanced themselves from the book, while Omid Scobie and Carolyn Durand, its authors, have repeatedly insisted the pair were not interviewed and did not contribute, despite a startling level of detail of their innermost thoughts and feelings.
However, buried in an "author's note" at the back of the book, is the intriguing admission: "We have spoken with close friends of Harry and Meghan, royal aides and palace staff (past and present), the charities and organisations they have built long-lasting relationships with and, when appropriate, the couple themselves."
The Mail on Sunday's legal team are understood to be examining whether it is evidence that the Duchess allowed friends to speak to the media on her behalf, which is central to the case - in which she could be called to the stand.
Mark Stephens, a leading media lawyer and partner at Howard Kennedy solicitors, said: "Essentially, that's a confession that this is as near as damn it to an authorised biography."
He said the Duchess could be questioned on the stand about whether she gave the green light to friends and colleagues to contribute to the book.
The Duchess is suing The Mail on Sunday for breach of privacy after it published part of a letter she had written to her father.