Aside from the fact that I had a massive crush on my English teacher Mrs Tate, I liked her because she was very encouraging when I started writing.

Ainslie Park High in Edinburgh was a prison camp for housing scheme [council house] kids. It produced labourers and typists. It wasn’t an academic school and I was not academically inclined.

I had mild dyslexia and concentration issues, so I was either very disruptive or very withdrawn. I found it a strain to sit in a classroom and take instruction, so when everyone else was doing maths, I was writing weird little stories or drawing strange pictures. Or I was being a general pain in the arse with the other like-minded clowns.

I used to write stories about the housing schemes, which I wrote in the vernacular. A lot of teachers discouraged me but Mrs Tate said: “This is great. Keep doing this. It’s brilliant.” She kind of gave me permission to write in a character’s own dialect and that’s how I wrote Trainspotting.

She said: write what you want to write, write what you know about, and understand that if you try and do something a bit out there, you’re going to annoy the establishment and get under the skin of authority figures in a visceral way. These were massive life lessons.

She was quite a left-leaning, political woman in her late 20s or early 30s and once she got us to do a school magazine. She encouraged us to write as we spoke and it had great cartoons. The deputy headmaster at the school hated it and banned it immediately.

I remember him having a shouting match with Mrs Tate in the corridor and she stood her ground. I felt bad for her having to take all that on her own but I was intimidated by the deputy head as he was the disciplinarian.

She despaired of my grammar and emphasised that you have to learn the basics before you can fly into the big league. That was a boring and painful lesson, which I didn’t take on until much later when I went to night school to do A levels in English, sociology and economics.

Nevertheless, she would laugh her head off at my writing. That was another thing I learned from her: it’s always good to be able to make a woman laugh.

I don’t remember sitting any exams. I wasn’t in certificate classes anyway as I was only interested in English and art.

I only got about 10 per cent of what I could have out of school and I left at 16 to work as an apprentice TV mechanic.

I remember meeting Mrs Tate in the street once and she said: “Are you still writing?” I thought that was a strange thing to say. I’d left school, why would I still be writing? But she said: “You should. You should keep on writing.”

I’ve never gone back to the school. Why would I? Apart from the friendships that I made, my experience there was very negative. In one class, I used to get the belt every single day. When I asked why, I was told that it was for when I did something wrong; it immediately de-incentivised me to behave. It was indicative of how the place was run.

Mrs Tate sent me a letter after I wrote Marabou Stork Nightmares. I sent her one back and I thanked her. When you get a teacher like that, especially in a school like that where you’re told that you won’t amount to much, it’s an incredible thing. It’s great to know that somebody gets you.

Irvine Welsh was talking to Kate Bohdanowicz. Performers, a play by Irvine Welsh and Dean Cavanagh, debuts at the Edinburgh Fringe Festival, 3-27 August, at the Assembly Rooms, 4.45pm daily. Irvine’s musical Creatives is on at the Pleasance Courtyard from 2-28 August