How did you get into teaching?
It was something I had always been interested in. I enjoyed school and thought teaching would be good fun. It was the early 1970s and most of the people I knew went into public service, teaching or social work. It sounds rather quaint but there was a feeling at the time that you should try to make society a little bit better. I had done an English degree at Cambridge and then I did a PGCE in English and drama at Nottingham.
Did you enjoy it?
They were different times, much more flexible and open. You could almost make up your own curriculum and make up a lesson as you walked into the classroom. I enjoyed the camaraderie of the staffroom. Teaching is a solo job but you share a lot of experiences and you are part of a team.
Why did you leave?
I became a head of department and had I stayed I would have been looking to go into what is now called management, and what was then called being a deputy head.
But I was keen to write: I used to put on a lot of shows and I was writing school shows and pantomimes. I had also been trying to write for television and I had got myself an agent. One day the careers adviser pointed out an advert for an assistant producer in the schools department at the BBC so I applied and got the job. I think I made a better television person than I ever would a deputy head.
What did the job involve?
Children's television wasn't exactly a backwater, but it wasn't mainstream TV, and they gave you a lot of freedom and just let you get on with it. The first set of programmes I made were primary programmes, such as Zig and Zag, and I learnt a lot from members of the crew.
I also did some writing for Grange Hill. That was a direct use of my teaching experience, and I tried to make sure at least one scene in every programme was set in a classroom. In quite a lot of Grange Hill you never saw a classroom.
After six years I left the BBC to set up Open Minds, one of the first production companies to specialise in making education programmes, and I did that for 12 years until the market disappeared with the move away from television for schools and towards internet-based resources. Then we moved into making programmes for CBeebies, soft education if you like. We wanted to bring the educational skills across but it's very different because the primary purpose isn't education.
How did an English teacher end up making maths programmes?
It started when Channel 4 wanted to make some key stage 1 programmes, and the idea was to look for stories that involved maths, such as Three Little Pigs. We created a series called the Number Crew and that gave us an impetus to look at how to bring stories to mathematics. We then developed an expertise in maths that we carried on into other series.
What impact has your teaching career had on your television work?
What you're doing both in the classroom and on television is saying: "Give me your time and your belief that we will do something worthwhile, and you will be rewarded." It is a sacred trust but it is easy to be boring.
Education is 90-something per cent motivation: if you engage a child in the right way they can learn anything and it almost doesn't matter what you teach. You draw on whatever you can to engage them - whether it is putting on a funny voice in the classroom or using modern television technology - because you're looking for something that connects the child to the learning. A lot of pre-school programmes are safe and unchallenging, but (his currrent series) Numberjacks it is engaging with the real world and the children enjoy the thrill.
Do you miss teaching?
Yes. It is one of those jobs, like fighter pilot, where you get instant job satisfaction. There is nothing so painful as a class that is out to get you, and nothing so nice as a class that is buzzing. Making a television programme is relatively lonely, particularly now I've moved more into writing. I miss the banter, the cut and thrust, and dealing with real people.
Who has been your greatest influence?
The colleagues I first worked with at the BBC. They were genuine craftspeople and enabled you to draw on their expertise, all underpinned by a belief in children.
What would you do if you were Schools Secretary for the day?
Let teachers breathe. I would remove a huge amount of target-setting and the obsession with grades, and say have faith in yourselves.
What will your epitaph be?
This man has written more songs about maths than anybody else. I have probably written about 200.
The new series of 'Numberjacks' starts on CBeebies in October. 'Numberjacks: Seaside Adventure' is now available on DVD
1989-: Open Mind Productions
1983-1989: Assistant producer, BBC Children's
1979-1983: Head of English at Pelham High School, London
1977-1979: Second in department at Waingels Copse School, Berkshire
1973-1977: English teacher at Isleworth Boys' Grammar School, Middlesex.