For 5000 years the river Nile has dominated Egypt. To mark the first anniversary of the fall of Egyptian president Hosni Mubarak, Edward Stourton travels along the Nile from the magnificent high dam at Aswan to the rich farmland of the Delta to explore the enduring undercurrents that have helped shape the country. While rulers come and go the Nile remains eternal and fundamental to Egypt's existence. The country gets 98% of its water from the river. Seen from the air the Nile cuts a narrow green strip through the desert and the vast majority of Egypt's population live within a few miles either side of its banks. How will the Nile and its people respond to the passing of another dynasty?