The forbidding black chair awaits its next nervous occupants. The quartet of contenders tonight will be grilled for two minutes on the history of American jazz, 17th-century English radicals Gerrard Winstanley and the Diggers, the cult supernatural TV series Buffy the Vampire Slayer and the life and times of medieval monarch Eleanor of Aquitaine. John Humphrys asks the questions and delivers the verdicts.