The whole atmosphere at my very small junior school was about enjoying learning. It had a library, a tiny library even to us at the time, but we were allowed in whenever we liked. It was exciting because it was like having a sanctuary where we could go to find out anything we wanted to about the world, and I loved it.

Highfield Junior was quite a rufty-tufty school, keen on us doing lots of physical activity. I was in the swimming team and we had to swim four times a day in an outside pool, whatever the weather. I smelled permanently of chlorine. We would be dragged around the country for competitions, and one of my memories of being little is of endlessly slogging up and down the pool. I could swim a mile at the age of 10.

We would always be off doing stuff outdoors, getting cold and muddy, collecting leaves, finding caterpillars to study, that sort of thing. Schools are so worried about health and safety and budgets now that they don’t do much of this any more. It is desperately sad for the kids themselves and not great in terms of the planet’s future.

It seems to me that if children are to be able to learn about, and care about, the natural environment, they have to be able to go out in it. If I were the new (Schools Secretary) Ed Balls, I would have kids out of the classroom every single day, and I bet they would love it.

Though I had never have imagined it possible before I got to her class, my very favourite teacher was Mrs Holt, who was in charge of the final year of junior school. She was famous for being absolutely terrifying and we were sure that she breathed fire.

But even though she was ferocious, she was also inspirational. She didn’t do marks out of 10, but would give out poor, which would be just awful, or good, very good and excellent. She was very parsimonious with her excellents, so when you got one you knew you had really achieved.

She loved literature. We learnt reams of poetry with her and would say it back in class. She inspired in me a love of books and a desperate desire to write. She taught us beautiful italic handwriting, with a proper italic pen, no smudges allowed.

Just as I had started on TV, the school very sweetly asked me back to give the sixth-form prizes. It coincided with the year that Mrs Holt was retiring. I didn’t tell her directly what she had meant to me, but what I did do - and I’m not sure she ever forgave me - was to stand up in front of the assembled girls and say: “There is something I’m going to tell you; you will never, ever have a teacher better than Mrs Holt.” The rows of girls just stared back at me and I could tell that she was still terrifying.

Secondary school was much bigger, with 30 kids per class and four or five classes in a year. There was a rigorous exam to get in, and the minute you got there all you did was learn to pass more exams. I hated it - we were being pushed into a sausage machine and the idea was to go to university, ideally Oxford or Cambridge.

I decided not to go straight to university. I thought there were other ways to learn things. So at 19, after working for a few months to earn some money, I headed off to Africa with a rucksack and pound;800. I came back having had a glimpse into the natural world that completely inspired me. That year in Africa, and Mrs Holt, took me in the direction I’m working in now.

• Kate Humble hosts `Springwatch’ and `Autumnwatch’ and has just been elected president of the Royal Society for the Protection of Birds. She was talking to Louise Tickle.