Clare Balding walks with the celebrated author and academic, Robert Macfarlane who takes her from his home in Cambridge out onto the Icknield Way. For a man known to love mountains, Robert explains how he's slowly come to love the tame lowlands of Cambridgeshire and how he now relies on climbing trees to give him height and views. While Clare is not tempted to join him at the top of an accommodating beech tree, she's happy to admire the graffiti left on the bark. Walking out in the summer sunshine Robert shares his fascination for the ancient tracks, drove-roads and sea paths that criss-cross the British Countryside. Producer Lucy Lunt.