- This is the Charnwood Forest in Leicester.

As a schoolboy, I grew up near here.

- It was the discoveries David made here in the 1930s that inspired his lifelong search to uncover the secrets of the natural world.

- When I was a boy, growing up in the Midlands, in Leicester, the rocks and lime stones you found in the east of the country were full of the most magical things.

You hit a stone, and it suddenly fell open.

And there was this amazing coiled shell, beautiful and extraordinary, and nobody had seen that for 150 million years except you.

So I thought it was very romantic and exciting.

And it appealed to the small boy's instinct of collecting things.

To be honest, I don't think I've really lost.

But anyway, I certainly had it then.

- The awe and wonder first experienced by that 7-year-old was nurtured by his academic parents.

David was the middle of three sons born to Mary and Frederick.

His eldest brother Richard, growing up to become an Oscar-winning actor and director.

The family lived in the grounds of Leicester University.

- Yes, here we are.

That was the university.

Well, it was as the press were quick to point out a lunatic asylum, and it was taken over by the University College, you see.

And we lived in that, which was the superintendent's house, his college house.

Then there's the big park, the Victoria Park.

And there's my father, he was principal of the University College in the 1930s.

And there he is, looking younger than me!

Though he didn't have any hair, but not since he was about 28, I think.

- David's early passion for the natural world won him a scholarship to Cambridge University.

This enabled him to indulge his growing fascination.

But though he would eventually go on to present and narrate hundreds of hours of films, surprisingly his long career in TV began quite by chance.

- I saw an advertisement in The Times for a sound radio job, which I applied for and didn't even get an interview.

But some week or so afterwards, I got a letter from someone said they got this new thing called television, and was I interested?

And then they said they'll pay me a thousand pounds to go on the training course.

And that was three times what I was being paid at the time in the publishers.

So I thought well I'll give it a go.