Piecing together clues from the natural and man-made landscape, Alan looks at the dramatic changes that have affected the British Isles from the Stone Age to the Industrial Revolution. The entire population of Britain could fit into a football stadium 8000 years ago. Today we probably see more people on the way to work than one of our ancestors would have seen in a lifetime. The clearing of forests for agriculture and the introduction of new species changed the landscape for ever.

• Alan Titchmarsh