The author of a controversial biography which claims the Prince of Wales's court is riddled with in-fighting has been forced to defend her book amid accusations that she has spent little time with Charles.
The book, serialised in the Times, portrays the Prince as a man afflicted by "insecurity", susceptible to bouts of despair and unable to control the feuding of his staff.
The latest instalment of Charles: The Heart Of A King, by Time magazine journalist Catherine Mayer, claims the Queen is concerned that her eldest son's activism would redefine the monarchy in a way the public will not tolerate.
But Clarence House officials have stressed that the biography has not been authorised by the Palace.
Speaking to BBC Breakfast, Ms Mayer said she spent "about six months trailing" Charles for a Time cover story and researched him further for the book.
She said: "I had some help from Clarence House to not only attend events that press could accredit for, but also to talk to members of his inner circle and his friends.
"After that cover story came out I continued researching. I went to every event that it was possible to get to.
"I've seen in the press reports that it's not true that I've been to a private dinner with him. It is true. I went to a small dinner that he held at Dumfries House where he invited some very wealthy people along in the hopes that they would support his charities."
Asked how much time she has spent with him "personally", she said: "I've sat down with him once and recorded a conversation."
Ms Mayer added: "By the standards of other journalists I have spent a lot of time with him."
The writer also revealed that she believes there is a "huge gap between the public perceptions" of Charles and who he actually is. The heir to the throne is more similar to his late wife Diana than most appreciate, she said.
She said: "She was the queen of people's hearts. He is very passionate and emotional and he actually wants to change things and heal. He uses the word 'heal' an awful lot. He talks about healing the world."
Over the weekend, a Clarence House spokeswoman said: "This is not an official biography, therefore, we have no comment to make."