Renowned author John le Carre delves into the dark and dangerous world of drug trials and pharmaceutical profits in his latest novel, "The Constant Gardener". In the afterword to the book he says that although his novel is a work of fiction and doesn'€™t reflect the actions of any real people, the real goings-on in the industry make his story seem like a "holiday postcard". Sue Valentine spoke to him, this is a transcript of part of their conversation.