Fifty years ago the world's first commercialjet plane, the Comet, was unveiled. Graham Boynton tells the story of the men who worked on the aircraft and looks back at the development of the British plane by the De Havilland company. He hears from the engineers who were responsible for its redesign after the disastrous crashes of 1954 and follows the dream of airtravel through to the development of Concorde. Producer Susan Marling