Artist Leon Kossoff is best known for his unmistakable thickly-painted pictures of London. But a new exhibition at the National Gallery displays some of his work inspired by other artists such as Poussin and Rembrandt. Philip Dodd sees the results. And the programme asks why the story of Noah and the flood has become a central myth for our times, from religious extremism to apocalyptic warnings about global warming. Scientists, theologians and writers, including Martin Palmer , Maggie Gee and Geraldine McCaughrean , diSCUSS. Producer Horatio Clare