Bestselling novelist Lee Child, writer and actor Kwame Kwei Armah and the director of Liberty Shami Chakrabarti talk to Mariella Frostrup to talk about Harper Lee's classic novel "To Kill A Mockingbird" as it turns fifty. They are joined by author Meg Rosoff and writer and journalist Diane Roberts to discuss race, class and prejudice in Harper Lee's phenomenally successful, and only, book. Producer - Sally Spurring.