After beating his own addictions, Eric Clapton founded a rehabilitation centre on Antigua to help others do the same. Mary Russell visits

He has been called many things including God, Derek, Slowhand and x-Sample but at Crossroads, he's plain Mr Clapton, patron of the drug and alcohol dependency centre he set up on the Caribbean island of Antigua, where he also has a home.

Eric Clapton has been down among the dead men, working his way through marijuana, black bombers, cocaine, heroin and hard liquor, producing some of the greatest blues music en route but halfway to wrecking his life in the process.

The rehab centre which helped him defy his own dependency is in Minneapolis and though the centre in Antigua is unique, some of its practices are similar to the Minneapolis course.

Built in 1998, Crossroads is set in one of the most remote though beautiful bays of the island backed by wooded hills and encircled by a horseshoe of coral which makes it difficult for boats with spying cameras to get close or indeed for clients to make a watery run for it.

When I arrive, I have to sign a document agreeing not to identify anyone I might meet at Crossroads nor to infringe on their privacy. Even the ornamental plaque with its list of donors - which included many famous musicians and influential organisations - was out of bounds.

The director of Crossroads is Tim Sinnott, a man with eyes as blue as the Caribbean who radiates an aura of calm authority in a place where many come having hit a wall of despair.

"One of the things we offer is a busy routine and activities that bring people in contact with each other. Addicts tend to cut themselves off from family and friends," says Sinnott. "Their addiction isolates them, so we have a lot of team games which means a top businessman playing softball with a taxi driver. Maybe they wouldn't normally meet socially but here they all have one thing in common: their addiction."

A sweeping, secluded driveway lined with palm trees leads to a white, porticoed entrance. The gardens, full of purple and pink bougainvillea, are well-tended, the pool a perfect blue. There is an air of quiet privilege to the place - until you enter one room which, horribly, reminded me of a Harley Street torture treatment centre I once visited. This is the detox area, and has the feel of a medical ward to it, with its hospital bed and round-the-clock team of doctors and nurses on call.

Detox treatment lasts three to five days: "We have a hot tub they use which gives them some relief: one side effect of coming off a substance is that people get severe physical pain," says Sinnott.

After that, the daily routine starts: up with the Caribbean sunrise at 6am, then duties which involve tidying rooms, rounding people up for breakfast, taking the roll call. This is followed by group sessions, sport, private counselling, meditation - and more group sessions, because this is where bullshitting flies out the window. "In the group, everyone has been there so there's no room for self-delusion," says Sinnott, himself a recovering alcoholic of some 20 years.

The 29-day course is structured. The week in detox is followed by a week spent breaking down barriers before people move on to the re-entry period when, close to the end, family members are invited to come for the weekend.

"How did Eric Clapton overcome his addiction?" I ask Sinnott, but this is a no-go area. "All I can say," he offers, "is that Mr Clapton wanted it done this way at Crossroads."

In fact, it is all well documented. He was married to Patti Boyd, former wife of George Harrison, when he went into rehab in Minnesota, and one of the hardest things he had to deal with there was her assessment of him. Up to that point, she had told no one of Clapton's behaviour.

"There hadn't been one minute, on any day, when he was completely sober so he had absolutely no idea how I felt," she told Ray Coleman, Clapton's biographer. Clapton was shattered: "Up till then," he told Coleman, "I was playing the role of Jack the Lad but when I heard what she'd written, I cracked." It was from this point that his real recovery began.

Patti Boyd spent five days in intensive therapy at the Minnesota Centre herself. Ironically, while he was in rehab she had "leaned on the bottle", fearing her husband might see her in a different light once he was sober. Perhaps she was right: they both went on to other marriages.

Crossroads isn't easy street, and had I been a client I might well have been looking to escape into a nice bit of literary fantasy, science fiction or maybe even some uplifting poetry, but no books are allowed unless they relate to the business in hand. There is a lot of work to be done, and there can be no soothing music either - even Clapton leaves his guitar behind when he comes calling, which isn't all that often. In fact, the nearest anyone might get to him is by watching the Crossroads video on which he appears - talking about his own addiction.

"He is our main benefactor," says Sinnott, "and he has raised some big money for us. BB King donated a guitar which Mr Clapton auctioned and that brought us $7 million [€5.9 million]."

The big question, of course, is what comes after Crossroads? The recovery rate is 49 per cent, which means more than half relapse. "The longer the treatment the better the chance of recovery," says Sinnott. "People can return to Crossroads a second time but not a third time. After that, we try to find something more suited to their needs and we're at the end of the phone all the time."

Crossroads has the feel of a small, select hotel, though its billing system is different: full board and treatment is $586 per day. Looking around the spacious grounds and beyond to the sparkling aquamarine sea, I couldn't help feeling this is a place far removed from the real world of Antigua where the ordinary person with a drink problem - and I don't mean the yachties or the sun worshippers - would find it hard to get together $50, let alone $586.

But that would be reckoning without the Clapton input. The eastern Caribbean islands - many musicians used the Air Studios on nearby Montserrat - have been a popular hideaway for rock stars. This may explain why locals in need are treated at Crossroads - a registered charity - for nothing, people from other Caribbean islands can get 75 per cent off and others can apply for a reduction of 50 per cent. Not only that, the island has a halfway house and while there, Antiguans are helped to get back into work through Crossroads' contacts with local businesses.

This is an island that throbs with reggae and soca, where music has been the food of the soul through all the hard times, and it is clear that the presence of a musician who has added to that legacy is one that is treasured.

"And there's another thing about this place," says Sinnott. "It has a good feel to it." When I recount this to the island's archaeologist, Dr Reg Murphy - whose family has Cork connections - he nods: "The Arawak [indigenous people] had a place there. I reckon they left some good things behind them."

• www.crossroadsantigua.org