Tubular Bells is the rock classic that soundtracked the spectacular 2012 Olympics opening ceremony as well as the notorious horror blockbuster movie The Exorcist and the lives of some 20 million fans since its first release in 1973, when it launched the fortunes of travel-to-telecoms tycoon Richard Branson. The man behind the music, the semi-reclusive Mike Oldfield, tells the story of its making to the legendary rock journalist Mat Snow.