LONDON - A new biography of Britain's Prince Charles has reignited debate about whether he is fit to become king, given his outspoken views and energetic activism.
The book also portrays a royal household riven with infighting, and an heir to the throne uncomfortable with the distant impartiality that has been the hallmark of his mother Queen Elizabeth II's reign.
The 66-year-old Prince of Wales, Queen Elizabeth's eldest son, has spent a lifetime in preparation for the throne.
But he has also carved out a distinct and highly visible role for himself in public life by wading into topics that rouse him, such as youth deprivation, the environment and alternative medicine.
Catherine Mayer, the author of "Charles: The Heart of a King" due out Thursday, is a former London bureau chief for the US magazine Time.
Her book claims he is "joylessly" preparing for the throne and has no appetite for a role that would curb his ability to speak out.
"Far from itching to assume the crown, he is already feeling its weight and worrying about its impact on the job he has been doing," Mayer writes.
Charles 'knight on a quest'
The book claims the prince has a "native insecurity", and that his Clarence House headquarters is riven with turf wars.
"The Boss", as his 161 employees call him, is reluctant to draw a veil over his convictions on subjects such as architecture, faith, organic farming and climate change.
"I only take on the most difficult challenges. Because I want to raise aspirations and recreate hope from hopelessness and health from deprivation," he told Mayer, who calls him "a man with a mission, a knight on a quest." However, "there will always be critics who take him for a parasite, an eccentric, a plant whisperer," she writes.
Charles's father Prince Philip is said to believe his son is guilty of "selfish behaviour" for putting his "cerebral passions" ahead of royal duties.
Clarence House stressed it had not authorised the biography and reserves the right to take legal action.
"Speculation about the Prince of Wales's future role as king has been around for decades but it is not something we have commented on and nor will we do so now," said a spokeswoman.
Mayer was permitted a brief interview with Charles and quotes several anonymous close friends, aides and opponents.
Detractors of the book's contentions are similarly making use of off-the-record insiders to slap down many of its claims.
"People who purport to know what he is thinking are just guessing," The Daily Telegraph newspaper quoted one source saying.
Prince 'driven by anguish'
The book's editor W. H. Allen said the biography revealed "a man in sight of happiness yet still driven by anguish," inspired by "passionate views that mean he will never be as remote and impartial as his mother." The problem is that in Britain, the monarch reigns but does not rule, with the democratically-elected government holding de facto power if not de jure.
Speculation about the prince's behaviour on the throne is certain to surge anew next month when the Supreme Court decides whether Charles's private handwritten letters to government ministers - dubbed the "Black Spider Memos" due to his heavy lines of annotation across the pages - should be made public.
The Guardian newspaper is seeking their publication, suspecting Charles of trying to exercise undue influence on cabinet members.
Royal expert Robert Jobson told AFP the debate swirling around Charles was a tempest in a teacup, with the prince more aware than anyone of the duties that come with the throne.
The prince's activism "is not a problem at the moment because he is not the king," the London Evening Standard newspaper's royal editor said.
"If he was behaving in this way when he is a monarch, quite actively outspoken, then it could be potentially - but I don't foresee that would happen."