Plot: Guildhall in the City of London is the setting when five more Mastermind champions return to the famous black chair to find out which two will join yesterday's winners in the final of this special tenth anniversary tournament. Leslie Grout (1981): Windsor Castle John Hart (1975): Athens and Sparta 750-394 BC Fred Housego (1980): The Normans AD 911-1154 Rosemary James (1978): Norse mythology Patricia Owen (1973): Art and architecture of Constantinople AD 330-1453