How did you get involved in the project?
I was asked if I'd be interested in working with the BBC Natural History Unit and, of course, I said, "Not half!" They had brainstorming sessions, and we had meetings about my interests. It soon became plain to them that I was a great fan of where I lived and that I've always been interested in British natural history, so we thought, "Let's do a big sort of history of the British landscape." I thought, "Well, that sounds like a modest starter," and so we went for it. Three billion years crammed into eight hours. Blink and you miss it!
Which came first for you, gardening or natural history?
The gardening I think came out of the natural history. When I was a boy, I joined the local naturalist society--we went birdwatching and pond dipping and all those sorts of things, and the two were inextricably entwined. I have to say, I don't see gardening as being divorced from natural history at all, at least I think that in a good garden it shouldn't be. The natural history for me is a valid and valued part of gardening, so it was partly going back to my roots and partly expanding my outlook, rather than going in a completely different direction.
Which of the places you visited during filming was your favourite?
That's almost impossible to answer--probably because the islands are so varied and so spectacular. Yesterday, I flew from London to Cornwall and back in a helicopter to do some filming, and it was a perfectly clear day. We went over Surrey, then on to Hampshire, Dorset, Wiltshire, Somerset, Devon and Cornwall. It was the most amazing trip. It's the variety that makes these isles so interesting. But we do have an astonishing landscape, whether it's the snow-capped summit of Ben Nevis in bright sunshine or the west of Ireland when it rains on the amazing flora in the Burren. The whole thing has been a revelation.
What did you hope to achieve?
What the series has done for me--and, I hope, for those people who watch it--is answer all the questions about why this landscape is the way it is and how it got like that. That knowledge fosters respect and also love and affection for a place. And I think that if you love something, then you're more likely to take care of it.
Do you have a favourite episode?
Oh no--I couldn't pin down one. You feel like a child in a sweet shop. The series is a voyage. It's putting the jigsaw of three billion years together. There are so many moments when you're saying to yourself, "Oh, I see. "And I loved those moments--the revelations. …