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.

Clearly we could devastate the world... as far as we know, the Earth is the only place in the universe where there is life. Its continued survival now rests in our hands

Birds were flying from continent to continent long before we were. They reached the coldest place on Earth, Antarctica, long before we did. They can survive in the hottest of deserts. Some can remain on the wing for years at a time. They can girdle the globe. Now, we have taken over the earth and the sea and the sky, but with skill and care and knowledge, we can ensure that there is still a place on Earth for birds in all their beauty and variety - if we want to... And surely, we should.

[W]hen we look at the graphs of rising ocean temperatures, rising carbon dioxide in the atmosphere and so on, we know that they are climbing far more steeply than can be accounted for by the natural oscillation of the weather ... What people (must) do is to change their behavior and their attitudes ... If we do care about our grandchildren then we have to do something, and we have to demand that our governments do something.

I just wish the world was twice as big and half of it was still unexplored.

Its about cherishing the woodland at the bottom of your garden or the stream that runs through it. It affects every aspect of life.

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