In a country house in England 10 citizens came for five days to live together and engage in a series of tasks. All their activities were videotaped, and three mental health professionals (psychiatrist, nurse, psychologist) were set the task of observing them closely over the whole period. The professionals’ aim was to work out which people had a past diagnosis of one of five common mental disorders: social anxiety, bipolar disorder, depression, obsessive compulsive disorder, or an eating disorder. The overall aim of the programme makers was to show how easy or difficult it was to identify mentally ill people just by looking at behaviour—to examine (as a portentous voice stated, over shots of Hever Castle), the “thin line between normality and mental illness.”

The end credits said that the Royal College …