There might be 60 million people living in Britain, but one-third of our landscape can still be classed as ‘wilderness’, virtually empty of people. Our mountains and moorlands, lowland heath and the Scottish Flow Country are some of the toughest habitats of all; places where life really does live on the edge. Join Alan Titchmarsh as he explores Wilderness Britain, realm of the magnificent golden eagle, a plant that fools insects, and Britain’s toughest bird.

• Alan Titchmarsh