I can mention many moments that were unforgettable and revelatory. But the most single revelatory three minutes was the first time I put on scuba gear and dived on a coral reef. It's just the unbelievable fact that you can move in three dimensions.

Now, I find that very difficult to reconcile with notions about a merciful God.

London has fine museums, the British Library is one of the greatest library institutions in the world... It's got everything you want, really.

I think a major element of jetlag is psychological. Nobody ever tells me what time it is at home.

Climate change will affect the whole of humanity, while terrorist attacks will only affect a small section of humanity. Of course, you wouldn't say that if you were related to someone who had been beheaded or blown up or murdered.

If my grandchildren were to look at me and say, 'You were aware species were disappearing and you did nothing, you said nothing', that I think is culpable. I don't know how much more they expect me to be doing, I'd better ask them.

Before the BBC, I joined the Navy in order to travel.