I want to nominate two people. One is a lady called Jenny Vanderstein, who was my biology teacher at Christ's College in Finchley, north London. It was a grammar school then and is now a comprehensive. She is one of the reasons I am doing medicine now. She said to me: "Of course, you are going to do medicine, aren't you?" That was a terrific confidence booster.
I was a bit squeamish about biology practicals. The big problem with science practicals is that you never really get the right result, you're never really sure what you're doing and it can put you off science in a big way. She was very careful to make sure the practicals worked.
I remember at one open day I had to dissect a sheep's heart. She could tell that I really wasn't too keen on this, so she did it for me. All I had to do was pin out the various parts of the heart and say what they were. A great teacher is sensitive to a child who doesn't really want to do some things but who still wants to take part in the subject.
I loved to bombard teachers with questions and Jenny was the first teacher I met who could handle any question. Most teachers find questions quite threatening, because if they don't know the answer they lose face. And yet that is one of the essences of teaching. The point about teaching is that interactivity - otherwise you might as well just give the kid a book.
In medical school, because I was known as the one who would always ask questions, the lecturers would come in and look around to see if I was there. If I was, you could see them physically shrivel because they thought: "Oh my God, he's going to start bombarding me with questions half way through the lecture."
When you ask a question, what you're doing is acknowledging your own ignorance. A lot of teachers make you think: "I don't want to show that I don't know this." So you keep your thoughts to yourself. Good teachers allow you to show your ignorance so they can help you with it.
There's something slightly evangelical about a great teacher. He or she wants to persuade you of something. For that to happen the teacher has to have viewpoints that aren't of the mainstream.
I remember Jenny teaching us stuff that was way beyond the curriculum, stuff to do with neuroscience that I wouldn't cover again until halfway through medical school. She didn't give a damn about the curriculum, she just pursued what she thought was interesting and taught it to us.
There was another very good teacher in that school, a history teacher who was very into Ireland. Ireland didn't feature at all in our history curriculum but we still got lots and lots about it. I remember in one lesson he was going on about the Irish famine and the things they had to eat when they were starving. It was so vivid that one bloke was physically sick in the dustbin immediately after the class. That's great teaching!
Jenny was in her 30s, but there was something very youthful about her. Teachers have to have a youthful side for kids to identify with them. It was an all boys school and most of the other teachers came across as very matronly. But she would chat to us on a much more one-to-one basis.
With most teachers you want to leave as soon as the class is over, but a great teacher captivates you.
My other best teacher was a guy called Geoffrey Thomas, who taught me philosophy at Birkbeck College. The great thing I got from him was not to be scared of very deep questioning. I think you should be suspicious of any teacher who can give you certain answers all the time. He was comfortable with uncertainty and could say: "Well, we don't really know the answer to this. "
Philosophy can be quite tough at first. But he made all our basic questions seem worthwhile by saying things like: "Kierkegaard said the same thing but in a different way." It made you feel you were in great company.
Because I enjoyed asking him questions, I used to offer to give him a lift home after the evening class. I pretended I lived quite near him but actually I lived miles away. We used to continue the class in the car on the way home - it was like extra teaching.
A great teacher makes you enthusiastic. He was so good I wrote a letter to Birkbeck saying: "You've got a great teacher here."
He was very keen to encourage lively debate, he wasn't worried about the class getting out of hand or people arguing with one another. Once you entered the class, the debate would start immediately, there was no time for small talk, we were just so involved.
Both Jenny and Geoffrey were interested in the bright people in the class. Teachers who are evangelical love a kid who wants to go on the journey with them. But it worries me what happens to the kids who aren't so bright or quite so enthused. Those kids need a different kind of teacher.
If you gave teachers higher salaries you would wipe the floor with the rest of the world. There would an economic and cultural renaissance in this country. What we need is a football-type transfer market so the very best teachers in the world want to come here. It's only when we start paying teachers what they're worth that this country will take off. People like Geoffrey and Jenny are doing a fantastically valuable thing.
Dr Raj Persaud, 33, has degrees in medicine, psychiatry, psychology, statistics, and the history of medicine, as well as diplomas in philosophy and health economics. He is an NHS consultant psychiatrist and tutor at the Maudsley hospital in London, a columnist for the Daily Mail and resident agony uncle on ITV's This Morning.