All our environmental problems become easier to solve with fewer people and harder - and ultimately impossible to solve - with ever more people.

Do we really require so many gardening programmes, makeover programmes or celebrity chefs?

What humans do over the next 50 years will determine the fate of all life on the planet.

I'd like to see the giant squid. Nobody has ever seen one. I could tell you people who have spent thousands and thousands of pounds trying to see giant squid. I mean, we know they exist because we have seen dead ones. But I have never seen a living one. Nor has anybody else.

The question is, are we happy to suppose that our grandchildren may never be able to see an elephant except in a picture book?

It is vital that there is a narrator figure whom people believe. That's why I never do commercials. If I started saying that margarine was the same as motherhood, people would think I was a liar.

Steve Irwin did wonderful conservation work but I was uncomfortable about some of his stunts. Even if animals aren't aware that you are not treating them with respect, the viewers are.