You'll discover in countries where women have control over their own bodies, where they have education, where they have birth control, where they have facilities and where they are literate, when those things happen, the birth rate falls.

I don't know [why we're here]. People sometimes say to me, 'Why don't you admit that the humming bird, the butterfly, the Bird of Paradise are proof of the wonderful things produced by Creation?' And I always say, well, when you say that, you've also got to think of a little boy sitting on a river bank, like here, in West Africa, that's got a little worm, a living organism, in his eye and boring through the eyeball and is slowly turning him blind. The Creator God that you believe in, presumably, also made that little worm. Now I personally find that difficult to accommodate.

I'm swanning round the world looking at the most fabulously interesting things. Such good fortune.

I would be absolutely astounded if population growth and industrialisation and all the stuff we are pumping into the atmosphere hadn't changed the climatic balance. Of course it has. There is no valid argument for denial.

The truth is: the natural world is changing. And we are totally dependent on that world. It provides our food, water and air. It is the most precious thing we have and we need to defend it.

The human population can no longer be allowed to grow in the same old uncontrollable way. If we do not take charge of our population size, then nature will do it for us and it is the poor people of the world who will suffer most

I had a huge advantage when I started 50 years ago - my job was secure. I didn't have to promote myself. These days there's far more pressure to make a mark, so the temptation is to make adventure television or personality shows. I hope the more didactic approach won't be lost.