The biggest rock star in the world is slightly smaller than you might think. Smaller, but going by the admiring female glances he attracts as he arrives to address the Oxford Union, still beautifully formed.

Jon Bon Jovi will be 40 next year but he's looking good on it. He's dressed in a black shirt, suit and dark silk tie, with slightly pointy boots. The smile gleams and the hair shines.

Jon Bon Jovi in Oxford He walks with a sort of rolling swagger, obligatory rock star shades in place above the cheese-cutter cheekbones.

Amy Harland, the Union president, welcomes Bon Jovi and gives him the conducted tour. They show him photographs of the Dalai Lama and Yasser Arafat. "I'm keeping good company," he murmurs.

"This is my first time in Oxford and I really don't know what to expect - but I love the danger!" he says, chuckling. They offer him a coke and ask him how he'd like to be introduced. He shrugs. "I don't mind - let's get it on," he says.

His childhood sweetheart and wife of some 12 years, Dorothea, and their children, Jesse, six, and Stephanie Rose, eight, have come along with today's Bon Jovi touring party.

I wonder if it was difficult, sometimes, being married to a man like Jon Bon Jovi. She looks across the room at him and smiles slowly. "No," she says. "It's not difficult."

Dorothea is not wearing a wedding band. Bon Jovi is.

His party also includes his manager and his chiropractor and Ted Emporellie, the man in charge of road travel. Like most people who work for the Bon Jovi organisation, Ted is from New Jersey and looks it. He could have stepped straight from the set of The Sopranos.

"This guy," he says, nodding at his employer, "is always doin' summpin'."

In the debating chamber, they applaud wildly when he swaggers in. He grins, milking it, as the president describes him as "A defining artist of our generation."

"Well, Malcolm X and Kermit have been here and I'm the latest Yank to address you," he begins. He goes on to speak of his parents back in blue-collar New Jersey:

"My folks saw the dream in me and they never discouraged it. There was no logical reason for me to believe that I was going to be in a band, but I believed it anyway." He speaks about passion - "my favourite word".

He tells them that after selling 40 million albums, he still has to fight and so do they. He mentions how he's had to start from the bottom as an actor and how his fame has hindered, rather than helped him.

"Money can't buy you love, and it can't buy you respect or class. It can buy you a pretty big house, though." The Union audience is loving it.

He speaks of his fame. "I don't make my kids applaud when I come downstairs in the morning," he says and then grins. "It's a good idea, though."

"My wife and kids never asked to be famous," he adds seriously. "So fame stops at the end of my driveway.'

He tells them to grow up but never to grow old. "The road ahead is as long as you make it," he says. "Make it worth the trip."

Afterwards, someone buys him a pint of lager in the Union bar. Pretty girls asks him to sign his name. His limousine is purring at the kerb.

It is, as Jon Bon Jovi says, "Good work if you can get it."