Plot: John Humphrys presents the celebrity version of Britain's toughest quiz. Four more celebrities take on the Mastermind challenge as presenter Tony Livesey, comedian Ava Vidal, presenter Monty Halls and pop-star turned broadcaster Reverend Richard Coles answer questions on the Jam, Buffy the Vampire Slayer, Jacques Cousteau and EF Benson's Mapp and Lucia novels