'I only enjoy bits of my job'

London: Prince Charles says he only enjoys "bits" of his job.

The heir to the throne, who turns 60 today, makes the admission in a fly-on-the-wall documentary about his life filmed to mark his birthday.

An insider on Charles at 60: The Passionate Prince, to be shown on BBC1, said the Prince is the frankest he has been about frustrations with his royal role.

Charles has been accused by some of inappropriate meddling when he uses his position to make himself heard on environmental and social issues. But it appears he feels his elevated status has its drawbacks.

At one point, he muses of his role as Prince of Wales: "I made it up as I went along... Each occupant of this position - which I can assure you isn't an easy one - has to decide what they particularly want to make of it."

"The most important thing is to listen to advice, which you can then decide whether you take or not."

Charles also reveals that he found studying at Cambridge University, while also taking a Welsh language course at the University of Wales and going on official tours around the world, a tough period in his life.

"It wasn't particularly easy. Good for the soul, good for the character," he says. "You either had to literally sink or swim, and that is what a lot of people never seem to understand."

BBC cameramen had unprecedented access for the 90-minute programme - the first major documentary about Charles for more than 14 years. They were there as controversy broke over his and Camilla's tour of the Caribbean by yacht, and for Prince William's RAF graduation.