When I was growing up in Nelson, a working class mill town near Burnley, Lancashire, my future, like everyone else's, seemed mapped out. It involved leaving school at 16, finding a menial job, getting someone pregnant and marrying them. Game over, pretty much.
In my case, the above didn't happen. I was lucky that Brian Wellock, my English and art teacher at Edge End High School, the local comprehensive, entered my life at a crucial point. He was the reason that I became an actor. It's thanks to him that I've had an entirely different kind of life.
Mr Wellock was more than just a teacher to me. He was an inspiration. He wore huge glasses and chain-smoked. He was a big noise in the local amateur dramatic society and he had a brilliant sense of humour. He was also the first teacher I'd known who didn't make Shakespeare seem like a foreign language and the first, too, who didn't patronise pupils, but spoke to them as though they were equals.
I remember my first real conversation with him vividly. I was 14 years old with a head full of football and not much else. But one evening I'd stumbled on the film Rebel Without a Cause and it had blown me away.
I saw Mr Wellock in the corridor next day and decided to tell him about it. He could have brushed me off or humoured me but instead he knelt down to my eye level and asked me what I'd loved about James Dean's performance. We chatted and he said: "Here's an idea. Why don't you come to the drama club?"
I auditioned for Billy Liar and was gutted to find myself in the chorus. But I persevered and later Mr Wellock cast me in the lead in The Thwarting of Baron Bolligrew, the Robert Bolt play. I was good at art, I was good at football, but finally I had found the thing that truly defined me.
There was so much more that Mr Wellock did, aside from just casting me from then on in leading roles in school plays. At 16, I applied to do drama at the local college. But he didn't rate the course and felt I needed to get out from the shadow of Nelson. He suggested a much better course at St Anne's in Blackpool and, although it was oversubscribed, he fought tooth and nail to get me on to it. I went on, at 19, to get a place at The Drama Centre in London, but those three years away from home at St Anne's, courtesy of Mr Wellock, were crucial.
I wasn't the only actor that he helped. I can think of five pupils of Edge End High School who went into the profession with varying degrees of success. Lee Ingleby, for example, who came five years after me, was also one of his protegees. We worked together in Life on Mars, the BBC series. Oddly, Lee played my father in the final episode.
I know for a fact that Brian Wellock watched that show. He died aged 63, in December 2006, following a routine operation and though, sadly, I'd lost touch with him over the years, I called his widow, Joyce, to tell her how sorry I was. She described how he'd watched that episode of Life on Mars and sat back on the couch with a look of complete satisfaction on his face to see Lee and I sharing the screen. "There again, he watched everything that you did, John," she said. "He was incredibly proud of you."
I was happy that I'd lived up to his expectations, but devastated by his loss. I was sorry too, that he hadn't been able to see me playing Vincent Van Gogh, the film I'd just finished making. Art and drama - his two passions. He'd have loved that.
After his death the local paper ran a story in which he was referred to in the headline as a local star-maker. But, of course, for those of us who had benefited from his encouragement, his belief in us and his passion for acting, Brian Wellock himself was the real star. No question.
John Simm, 38, is well known for his roles in dramas including State of Play and Life on Mars. He'll be seen next inThe Devil's Whore, a Channel 4 period drama. He spoke to Daphne Lockyer.