Story of ex-addict with a starring role among gallery's national icons

Joe Mocham makes an unlikely national icon. At 37, he boasts neither fame nor fortune, and has spent most of the past decade unemployed and addicted to heroin, living at a series of hostels for the homeless in Brighton.

There was, therefore, some surprise when Mr Mocham received an accolade traditionally reserved for the greatest of great Britons: this week, he became the latest inmate of the National Portrait Gallery.

"At first, I thought it was a mistake, or a joke," he recalled yesterday. "When it finally sunk in, I felt very proud. I hope to get up to London to see it one day."

Mr Mocham's trip from the streets of Brighton to the national collection began one morning in June, as he walked his collie, Sandy, along the seafront. A stranger asked if he would be willing to pose for a picture. That stranger turned out to be a photographer called Richard Boll; and he wanted a shot for the national gallery's annual photo portrait prize. Last week, Boll's photo, Joe, beat 2,000 entries to win the prestigious £12,000 gong.

Mr Mocham was brought up in Banbury, an Oxfordshire market town, where his dyslexia led him drop out of school to work shifts in a bakery.

He spent most weekends during the 1980s experimenting with LSD, and moved to Brighton in 1994 after the breakdown of a relationship. Shortly afterwards, his father died. "He left me some money, and you know how it is: when you've got money you've got a few friends," he recalls.

"I quit my job, and started mixing with a crowd who were into heroin. Before I knew it, I'd blown all the cash, £33,000, in six months. I regret that decision more than anything; getting into smack cost me 13 years."

During that time, Mr Mocham lived at several homes in Brighton with his girlfriend, Emma, another heroin addict. He recalls a chaotic existence, punctuated by the deaths of several close friends, and a house fire that destroyed all their possessions. "Once you're on heroin, they class you as eligible for incapacity benefit, and then it's really not worth trying to work; in any case, you don't want to. It's the devil's drug. It takes over your life."

The party ended when Emma died from a heart attack induced by a drug overdose. Her loss devastated Mr Mocham, and contributed to his fiery mood when Boll took his photo in June (that day would have been their anniversary). But it also spurred him to give up heroin, and he has now been clean for 10 months.

Salvation may lie in Kerriena, a pretty 23-year-old mother-of-four who has been Joe's girlfriend for four months. Boll gave the couple £500 from his winnings, which they will spend on Christmas. Pointing to a new ring on Kerriena's engagement finger, he says: "It's the smallest diamond in the world and we're calling it a friendship ring. But she wants to get married and I'm getting on a bit. With all that's happened to me lately, who knows?"