John Simpson, one of the BBC's best-known foreign correspondents, has been at the heart of breaking news for more than half a century. A frontline witness of history, the World Affairs editor has dodged bullets and cheated death from Iraq to Afghanistan. In a highly personal Panorama, John looks back over his 50-year career, revisiting the people and places that have impacted on him most, as he reveals his thoughts on the challenges for the future.