Top Gear Africa Special

Part one of two. A search for the source of the Nile in Africa

In the first of a two-part special edition of the motoring show, Jeremy Clarkson, Richard Hammond and James May visit Africa on a mission to find the definitive source of the Nile, the world's longest river, which spans more than 4,000 miles. The trio believe they can do a better job than explorers who claim to have discovered the waterway's starting point by travelling further and faster than previous efforts - but the only tools at their disposal are determination, ingenuity and three ageing estate cars