Heather McKelvey taught me A-level art. I did A-level maths, physics and chemistry, too. They had a kind of rigour and a structure, then we'd go up to the art room. There were only three of us. It was like a free zone where you could say what you wanted and do what you wanted - it was that kind of incredible freedom that she gave us.
I responded to free spirits. Heather McKelvey's world was a world of its own. It was much more by suggestion and there was a lot more emotion in the way that she taught. She'd say: "Have you seen this?" and it might be a book of Paul Cezanne's watercolours. I guess teaching art she had to be more associative and talk more in symbolism and emotions - but, boy, it was exactly the language I needed to hear.
She would say, "I want you to do a project inspired by this line from T.S. Eliot," or something like that. My background was quite working class, with no literary references at all, no books like that. So suddenly to be in a world that was so intellectually stimulating was just great.
The school was run by nuns. They treated us like kids even when we were 17, whereas she treated us like adults. I remember her talking to us about moussaka at dinner parties, and I'd never heard of dinner parties. So she managed to conjure an adult world beyond school which, if St Louis hadn't been such an oppressive, nun-based system, we might have already thought of ourselves.
She was probably 24 or so - that was the other crucial thing. Heather was cool and dressed modern and down to earth, like us. We were allowed to call her Heather. We could identify with her, there wasn't a glass wall between us.
I think the very idea of aesthetic education and an interest in modernism clashed with some of the nuns' ideas. In English, we were told not to read James Joyce, because he was dangerous and modernist. You would go up to the art room and we were encouraged to mainline modernism. That idea that selfhood could be fractured and multiple, all that stuff - it was exhilarating.
Creativity has been a real driving force for me. It's fuelled me even when there's the shit of the film industry that you have to deal with. I think she managed to convince us of that, that this was the thing to aim for. I'd already stopped believing in God at that point - that was already gone - but I think maybe she gave us something else to believe in, which is the joy of creativity.
I just loved to learn and I had a brain like a sponge and I wanted to suck everything in. I was also good, I got top marks in everything. Like many schools in those days - I finished in 1983 - there was loads of bullying going on, absolutely loads.
I was a skinny little arty-brainy boy, I just constantly got called "poofter" and they'd beat the crap out of me, but it was loads of people - not just me. It was a hierarchical, very class-bound school. In the art room there was none of that. It was much more meritocratic and about how well you drew or responded to Picasso.
It's an archetypal story - when you discovered creativity you felt a bit strange and alien and didn't fit in. Here was a world, in the art room, where you could fit in and everybody was strange. It made you feel great and not like a freak.
About five or six years ago me and my friend Sean Quinn, the other guy in the art class, went to see Heather and we caught up and got drunk, which was very nice. She opened a little door in my head which has never closed.
Mark Cousins was talking to Henry Hepburn
Born: Belfast, 1965 Education St Joseph's Primary, Belfast; St Louis Grammar School, Ballymena; University of Stirling, film and media studies and fine art
Career: Film-maker and author. Wrote and directed The Story of Film: An Odyssey (2011), a 15-hour documentary series. Established the 812 Foundation with Oscar-winning actor Tilda Swinton, introducing Scottish primary children to classic, world and avant-garde cinema.