As Mastermind celebrates its 20th anniversary, Magnus Magnusson questions this year's first contenders in the Great Hall, University of Reading: Alice Hobbs (teacher), children's literature since 1850; Christopher Wright (retired despatch clerk), Second World War in Asia and the Pacific; Jacqueline Pearce (information technology specialist), Greek mythology and heroic legend; Michael Forder (freelance editor and proofreader), life and works of Louis Armstrong.