Prince Charles has discussed with the Queen the "sensitive matter" of what sort of king he should be, royal aides disclosed before publication of a biography that explores the Prince's preparations for kingship.
Sources close to the Prince have said there is "no one" other than his mother with whom he would talk about his plans for the monarchy.
Clarence House is preparing for the publication on Thursday of Charles: The Heart of a King by Catherine Mayer, a journalist for Time magazine, which is expected to include the thoughts of his courtiers on how he will approach his eventual role as sovereign.
The Prince's future is also likely to be discussed in a second book, to be published this month, by the former Downing St communications director Alastair Campbell. Winners and How They Succeed is understood to include a chapter on the Queen, based on Campbell's experiences in Downing St and on recent conversations with royal aides.
Mayer claims the Prince is "joylessly" taking over more of the Queen's royal duties. He feels so passionate about the many causes he champions that, in the words of one courtier, ascending the throne will be like "prison shades" closing for him.
In an article for Time she said: "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."
But sources close to the Prince said anyone who claims to have insight into his thoughts on kingship is merely "hypothesising" because "there is no one other than his mother with whom he would discuss such a sensitive matter".
Mayer's book is also expected to address the belief in some quarters that the Queen should bypass her son and make her grandson, Prince William, her successor. She quotes the Prince saying that: "If you chuck away too many things, you end up discovering there was value in them."
Among friends of the Prince Mayer spoke to was actress Emma Thompson, who described dancing with him as "better than sex" and the former chief rabbi Jonathan Sacks, who described him as being "ahead [of] and behind his time. He's not of his time".
James Sommerville, who co-founded the design company Attik with a £2000 ($4,155) loan from the Prince's Trust and became vice-president of global design for Coca-Cola, told Mayer the Prince is so entrepreneurial that "if he was in industry, he would be a Branson or the late Steve Jobs".
Extracts from Charles: The Heart of a King have not been released ahead of serialisation but publisher WH Allen said: "This book offers fresh and fascinating insights into the Prince's first marriage which did so much to define him, and an assessment of his relationship with Camilla, the woman he calls, with unintended accuracy, his 'dearest' wife."