I wouldn’t say that Cambridge Jones is blasé about the celebrities he photographs in the course of his work, but he certainly keeps things in perspective. “It’s a funny thing, fame,” he says. “I tell my mum and dad that I interviewed so and so, and they say, ‘Who’s that then?’ People’s idea of who’s famous is so different.”

But when you hear that the Queen has his photographs in her private gallery, and that he has been doing the Blairs’ family Christmas card, you wonder if he’s understating his connections.

When he left Oxford University in 1988 with a degree in politics, philosophy and economics, he was passionate about photography, but never dreamed that he might make a living from it.

He moved to London to go into market research, setting up his own company specialising in TV focus groups, then started two bars in Soho. Then, after ten years of working life, he sold up and moved to a small Greek village with his wife, an academic, and his two small daughters. “If you are at all creative, it eventually destroys your soul,” he said, “because you are asking other people’s opinion of creativity. Eventually, you think ‘I need to go out and do something else’.”

He had been “obsessed” with photography since the age of 14, and had tried to persuade famous people to pose for him. “The first time I tried, I knew no one, but by the time I was older I knew more people. It was quite bold, in a way. If I didn’t know someone, I knew someone who knew someone…”

But wasn’t he nervous approaching people like Cliff Richard or Franz Ferdinand?

“That’s never bothered me. I have to make them relaxed, to get a good photograph. There’s no room for me to be nervous.”

He had a tempting question for his chosen celebrities – what’s your favourite piece of music? The result was Face The Music, a book and exhibition featuring 100 famous faces, from Desmond Tutu and Tony Blair to Cliff Richard. As people toured the gallery they could stop at each portrait to hear the subject’s choice of music through headphones. It was his breakthrough into the big-time, and now he has settled in Jericho, near Worcester College, where his wife is a don.

But he is clear that celebrity photography is not his main aim in life. “My real love is to wander around India or China with a camera. The fact that I get to photograph politicians and actors is an accident.”

He has plenty of amusing stories of dodging publicity people to get to his celebrities. But he when he finally meets them, he finds that they are just ordinary people. Two years ago, he was chosen by the Prince's Trust for its latest project, Inspired By Music. Launched last weekend, the book — to be followed later by an exhibition — features celebrities’ personal reflections on how music changed their lives, with each choice of song reproduced alongside Cambridge’s portraits.

Kevin Spacey, for example, chose Frank Sinatra's In the Wee Small Hours of the Morning, Al Pacino went for You’ve Got to be Carefully Taught by Rodgers and Hammerstein, while Tony Blair plumped for Ave Maria.

He also photographed not-so-famous young people who have been helped by the Prince’s Trust, which will benefit from royalties. Jamie Turner, for example, whose dream of working in the music industry was supported by the trust, appears alongside Ozzy Osbourne, Take That, film stars and politicians.

Cambridge has a personal reason for joining the project, having been adopted at two-and-a-half. “When I had my own kids, it led me to see clearly that ‘There but for the grace of God’…”

For the book, he spent a year touring the world, chasing celebrities from LA to Miami and back, but was also inspired by the trust’s work.

“I have been lucky in life, given what happened to me, and what could have happened to me. It’s giving a chance to people who thought that they had lost that chance.”

* Inspired by Music is sponsored by Starbucks and is being sold in its coffee shops, as well as bookshops, at £19.95. All money from books bought in Starbucks goes to the trust.