Lucy Worsley, chief curator of the historic royal palaces, looks at the room that has had more names and been through more changes than any other in the house. She tries out the communal medieval great hall, holds a candlelit tea party in a Georgian drawing room, explores the development of taste in a grand country house, discovers the wonders that gas and electric lighting brought to the Victorian parlour, and experiences leisure 1950s style. Includes interviews with historian Amanda Vickery and writer Adrian Tinniswood.