In the late 1930s the Lancashire town of Bolton witnessed a ground-breaking social experiment. Over three years, a team of ninety observers recorded, in painstaking detail, the everyday lives of ordinary working people at work and play - in the pub, dance hall, factory and on holiday. Their aim was to create an 'anthropology of ourselves'. The first of its kind, it later grew into the Mass Observation movement that proved so crucial to our understanding of public opinion in future generations.

The project attracted a cast of larger-than-life characters, not least its founders, the charismatic and unconventional anthropologist Tom Harrisson and the surrealist intellectuals Charles Madge and Humphrey Jennings. They were joined by a disparate band of men and women - students, artists, writers and photographers, unemployed workers and local volunteers - who worked tirelessly to turn the idle pleasure of people-watching into a science.

Drawing on their vivid reports, photographs and first-hand sources, David Hall relates the extraordinary story of this eccentric, short-lived, but hugely influential project. Along the way, he creates a richly detailed, fascinating portrait of a lost chapter of British social history, and of the life of an industrial northern town before the world changed for ever.