Prince Charles and Princess Diana’s wedding     Photo: www.bbc.co.uk

The Prince was racked with doubts about his doomed marriage, according to the unauthorised biography, and apparently said he was "desperate".

Prince Charles nearly jilted Princess Diana at the altar, it has been claimed.

The Prince of Wales was racked with such doubts about his doomed marriage that he was close to calling the wedding off the night before he walked down the aisle.

The revelation came in a book by Catherine Mayer, whose unauthorised biography Charles: Heart of a King is published on Thursday.

The book claims Charles told a member of his inner circle he “was desperate”.

The future Princess, to whom he had been engaged for five months after a brief courtship, was “not the jolly country girl he had assumed”, but instead a vulnerable, complicated woman already suffering from an eating disorder.

The Daily Telegraph revealed that the Prince is said to have told his confidant: “I can’t go through with it, I can’t do it.”

Lady Diana told her own biographer, Andrew Morton, that she confided in her sisters, telling them: “I can’t marry him, I can’t do this, and it’s absolutely unbelievable.”

They told her it was too late to pull out because “your face is [already] on the tea towels”. But, says Mayer: “She had no idea her bridegroom also had to be coaxed to the altar.”

The book is also said to contain fresh evidence about the extent to which the Prince of Wales trusted Jimmy Savile, later unmasked as one of the worst predatory paedophiles the country has ever known , even asking him to read his speeches for him to give him his thoughts.