What is the best piece of advice that you have been given?
Without good behaviour in school, little can be achieved.
Who has been your biggest influence?
David Lowther, who was head of the geography department when I started teaching at Eton. During the time he was head of department and the time I was head, it was easily the biggest department at the school, with over 100 pupils a year opting to do geography at A-level. He set high standards in teaching and he showed me how to do it. In those days schools like Eton didn't take people with teaching qualifications. So the first class I ever taught was a group of expectant Etonians and it was David Lowther who saved my bacon by telling me what to do.
What was your worst moment in teaching?
There have been two. One was the tragic murder of the daughter of a teacher. The other was on 26 December 2004, when I woke up to the news that my entire cricket team and lot of staff had been caught up in the tsunami. One parent very sadly drowned.
Which pupil are you most proud of?
I am always proud of the ordinary pupil who achieves something out of the ordinary. I have come across quite a number of those in the past 35 years, who through hard work have made it to a very good university. It is impossible to single out pupils, but Old Harrovian Jamie Murray Wells, who straight out of university founded Glasses Direct, now Europe's largest online glasses retailer, is outstanding.
What is your career high so far?
Harrow winning the national Senior Maths Challenge competition this year.
What would you been if you hadn't become a teacher?
I think I would have become a barrister. That was what I was considering. Before I even had the chance to enrol on the course I was offered a temporary job at Eton, and I never left teaching.
What do you do on a Friday evening?
In a boarding school, Friday evening is the same as any other evening. I go to a concert or a play. In the holidays I watch DVDs of The Wire.
What is the worst excuse you have ever heard?
The boy who, seen wearing trousers and jacket that were far too small for him, said it was not his fault he had grown.
Barnaby Lenon recently retired as headmaster of Harrow School. He began his teaching career at Eton College and was head of Trinity School in Croydon. He is the new chair of the Independent Schools Council.