There's nothing Gillies MacKinnon likes more than making films. And he is making plenty of them, writes Donald Clarke.

The first thing to say about Gillies MacKinnon is that he is 55. This is worth mentioning because, having graduated from film school in 1986 and made his first feature (for the BBC) in 1990, the bare facts suggest he should be one of Britain's hip young film-makers.

Speaking after a screening of his new picture, Pure, at Dublin International Film Festival last month, the softly spoken Glaswegian fills in the missing years.

"I did play around with cameras at art school, and even then I think I knew this is what I was meant to do," he says. "But it was frowned upon in those days. Making films was seen as a lesser thing to do than painting. When I left college I became a teacher and then a detached youth worker in London. And I also developed a sideline as a cartoonist."

You can imagine him as a youth worker. He has a kind, easy manner, but there is a suggestion of steel beneath, a suggestion that you would be ill advised to cross him (then again, that might just be the accent). His background working with troubled children will have come in handy for making Pure, which is concerned with heroin use in the East End of London. Unfortunately, it's not very good. So let's stay off the subject for as long as possible.

"One day I woke up and thought there's something I've forgotten here," he says, continuing the story of his midlife change in direction. I'm working to release other people's abilities, not mine. So I applied to film school. And to my great horror - I had two small children at the time - I was accepted. It was a very foolish thing to do."

In the 14 years since his first TV project, the Jimmy McGovern-scripted Needle, he has made a staggering 12 films, including three in Ireland: The Playboys (1992), Trojan Eddie (1996) and 2001's still unreleased The Escapist. He must have been making up for lost time.

"It did come from that momentum, yes, but also from a very primitive fear of failure. I am reassessing that in myself now. But, looking back, I can't honestly say I have made a film I shouldn't have made."

Indeed, it is an impressive body of work. Alongside the Irish projects are pictures such as Regeneration, his superb 1997 adaptation of Pat Barker's novel of the first World War, and 1996's Small Faces, a successful attempt to convey the energy of 1960s Glasgow youth culture.

All his work shows a great talent for bringing the best out in actors, something that Steve Martin saw in The Playboys and that persuaded him to lure the director to Hollywood for 1994's modestly diverting A Simple Twist Of Fate. "Hollywood was a good experience," he says. "But what I was doing was not something I uniquely could do. The things that were being offered to me were also being offered to 100 other people. And they could all have done the work as well as me."

The lifestyle didn't tempt him? "The day you recognise they've got you is the day you've got to make your decision about staying. They always treat you well: they send you a nice town car, take you to the best restaurants. I was living this lifestyle, and then one day I was going to the airport and, instead of a town car, this funny little car arrived. And I thought there's been a mistake, this isn't right. I caught myself thinking like an idiot. I knew then it was time to go back to Glasgow."

Based on a script by the journalist Alison Hume, Pure, whatever its eventual shortcomings, must have sounded like the ideal MacKinnon project. Telling the story of a young boy's attempts to wean his mother off heroin, it brought him back to material he had first dealt with in Needle, an altogether more robust treatment of the drugs issue.

"I had to convince myself that it was different from Needle," he says. "I initially thought I can't do this, I've made a film about heroin before. But when I was confronted with the reality that the film was going to happen next week, I realised that this was, firstly, a film about the relationship between a child and his mother. And that became the focus for me."

It is certainly a deeply felt piece of work, featuring a fine performance by the juvenile lead, Harry Eden, but it is sentimental, old fashioned and wildly implausible. The picture begins with the 10-year-old hero cooking up his mum's junk under the impression that he is administering medicine. For someone so smart, he's pretty dumb.

"Well, if you have a problem with that, then nothing I say can help you. The boy is in very serious denial. He cannot associate these things with his mother. That veil will get ripped from his eyes during the drama." He seems slightly hurt that I'm not getting on board, so I let it be.

Of course, if you don't happen to care for a Gillies MacKinnon film, there will always be another along in a minute. He is trying to get back to writing his own scripts, and The Escapist, starring Jonny Lee Miller, will finally appear on TV as a Sky movie in the near future. What keeps him going? "I found something I was born to do, which is direct films. Drive me down to that set in the morning and just watch me smell the gunpowder and come to life."

Pure opens at the Irish Film Centre, Dublin, on May 2nd