Sarah Montague speaks to Sir John Tavener, one of Britain's most celebrated composers. He says his music is for God - even referring to it as a form of divine dictation. Forty years ago, his work was sometimes dismissed as bland, populist, new age. But over time he has defied the critics - the Protecting Veil was one of the biggest selling classical albums ever, and his Song for Athene was played at the funeral of Princess Diana. Having been ill for much of his life, he says that everything changed after he nearly died from a heart attack six years ago. How did this experience affect his view of life, his music, and his faith?(Image:Sir John Tavener (left) and Simon Russell Beale. Credit: BBC)