He would breeze along the corridor in a tweed jacket, humming or whistling and occasionally bowling an imaginary cricket ball. Bruce Smith was about 40 years old, kind, friendly and content with his lot. He was my English and drama teacher in my last few years at Winchester House School in Northamptonshire, England, and he had a huge influence on me.
Mr Smith wasn't a strict disciplinarian but we certainly didn't run rings around him. He had a big voice but rarely shouted. When he did, I felt bad - we all did, as if we had let him down, because we liked him so much. Not many teachers achieve that.
He did all the school plays, some of them ambitious and spectacular, including big musicals such as Oliver! and Guys and Dolls. But every one of his lessons was like a performance. When he read aloud he would put an awful lot into it and get right into the characters. He was entertaining and inspiring.
I remember when we were reading The Hobbit and he took the part of Gollum. He did it brilliantly, bringing the character vividly to life. The Lord of the Rings films brought those days back to me and made me think about Mr Smith. All those years ago, he was playing Gollum just the way Andy Serkis plays him in the films.
Mr Smith was an intelligent teacher who knew how to get the best out of his students. He wanted us to do well and I never saw him pick on a student or criticise a weakness.
My handwriting was truly appalling - I was obviously destined to become a doctor - but Mr Smith never gave me a hard time over it. He told me I would have to be careful in exams but he didn't go on and on about it, and instead concentrated much more on what I had actually written.
His approach was refreshing and confidence-boosting, unlike other teachers who focused only on my handwriting. I didn't need anyone to tell me my handwriting was bad.
Mr Smith had another reason for not being too bothered about my handwriting. It was the late 1980s, the early days of computers, and Mr Smith said to us: "You'll soon be typing everything and handwriting won't be so important." He was right.
His classroom was also the school library so we were surrounded by books. Perhaps because I was an only child, I was a voracious and advanced reader for my age. Mr Smith encouraged me. He would bring books in from his home, including some by Graham Greene. I would finish one book, hand it back to him and he would bring in another one the next day.
Although I went on to study medicine, he gave me a love of books that has stayed with me to this day. He also gave me a love of teaching and taught me the importance of performing, of slightly exaggerating, which can be a good thing if done in the right way and in the right circumstances.
This has really helped with my TV work because being on television is a performance; it's not strictly me that you see but a parody, almost a caricature. It's also helped me socially and in life generally - it showed me a certain way to behave.
It's strange to think that after all those years Mr Smith is still influencing my behaviour. And I can still hear him playing Gollum.
Dr Christian Jessen is a doctor in a London clinic and presents Embarrassing Bodies and Supersize vs Superskinny on the UK's Channel 4. His Guide to Growing Up is available in paperback and ebook. He was talking to David Harrison
Dr Christian Jessen
Born: 4 March 1977, Hammersmith, London, England
Education: Hurlingham School, London; Winchester House School, Brackley, Northamptonshire; University College London
Career: Doctor, writer and broadcaster.