"There has been ill-informed speculation recently, in your columns and elsewhere, about the attitude of the Prince of Wales to the role of sovereign," Charles' private secretary William Nye said in a letter to 'The Times' after the newspaper serialised excerpts from Catherine Mayer's 'Charles: The Heart of a King'.
It adds: "His Royal Highness has always preferred not to comment on matters which relate to a future whose date is unknown, and would arise only after the death of his mother [Queen Elizabeth II]".
"Should he be called to the throne, the Prince of Wales will be inspired by the examples of his mother and grandfather, while drawing also on his own experience of a lifetime of service. He will seek to continue his service to this country and the other realms, to the Commonwealth and to the wider world".
Mayer's biography has claimed that "in defining his role as heir apparent, the 66-year-old prince has signalled a redefinition of the monarchy. Some courtiers - and the [Queen] herself - fear that neither the Crown nor its subjects will tolerate the shock of the new".
Mayer, a journalist for 'Time' magazine, has hit back at Clarence House's attempts to belittle her work, by suggesting she had exaggerated the amount of time she had spent with the prince.