Sue MacGregor talks to playwright David Edgar and novelist Helen Cross at the Birmingham Book Festival about their favourite books, including titles by Graham Greene, Anthony Trollope and Naomi Wolf. Books featured in this programme: David's choice: The Warden by Anthony Trollope, Penguin Classics Helen's choice: The Treehouse by Naomi Wolf, Virago Press Sue's choice: The End of the Affair by Graham Greene, Vintage Classics.