John Cale, Heroin & Wales

I was looking for an innovative way to look at the heroin problem in Wales. Who better to ask than John Cale, the Welshman behind the Velvet Underground's classic track Heroin? The surprise was he actually said yes.

It was a bit of a shock when John decided to take time out of his work at the Venice Biennale to do the programme. We were looking for a presenter with experience of drug use - and we tried him on the off-chance he'd be interested.

He was instantly enthusiastic, and moved heaven and Earth to make it happen. I think he was genuinely interested in the subject - and doing the programme gave him a first-hand insight into a side of his native Wales which he would otherwise probably never see.

The result, Heroin, Wales and Me, was screened as part of the Week In Week Out current affairs strand on BBC One Wales this week (it's still available on the BBC iPlayer)

You get a lot of different reactions when you tell people you're working with John Cale. Very often the response was "John who?" Even "The Velvet what?"

What was surprising about that was it came from heroin users and ex heroin users. After all, didn't the Velvet Underground write the soundtrack to shooting up!

I know drugs aren't glamorous and cool - but I did see Trainspotting. Somewhere in the back of my mind I assumed that people injected to the strains of Heroin or I'm Waiting for the Man. That there was some kind of pleasurable ritual to the whole thing.

The world I explored with John Cale was much darker. In the rundown post-industrial towns of South Wales, and the backstreets of Cardiff and Swansea, we came in contact with a the dark side of drug use. Teenagers shooting up because their mates do it, because there's nothing else to do, because they are blocking out the pain of an abusive past. Adults trapped in a downward spiral of drugs, crime, prison and more drugs.

You can't imagine many of them studying the best 1960s tracks to inject to - mostly they were too busy finding the cash for the drugs they craved.

John Cale's not a man to show his emotions lightly - but he was clearly disturbed by what he saw. The broken lives he witnessed in South Wales were a million miles from his experiences of drugs. Back in the days of the Velvets he saw them as an experiment - something to enhance the creative process he was engaged with in New York. And - he told me - they helped him stay up later and work longer.

He admits he "got in over his head" - cocaine and alcohol eventually got in the way of his work and he says he lost his sense of humour. He gave me footage of a concert in Germany in 1984 where he was clearly completely incapacitated by drugs - mumbling into a microphone with a piece of carpet held over his head.

Now he finds that kind of thing painful to watch - and he's ditched drugs and alcohol completely. Instead he works out in the gym - and runs marathons up the stairways of the skyscrapers in Los Angeles where he now lives.

• Heroin, Wales and Me

Nick Skinner is the director Wales, Heroin and Me featuring John Cale, first broadcast on BBC One (Wales) on 16 June 2009.