The spirit of the early Mass-Observation, its concern for understanding issues of everyday life, and its ambition to lay the foundations for a new sort of social science are well conveyed in a Penguin Special published half a year before the outbreak of war, Charles Madge and Tom Harrisson's Britain, by Mass-Observation (Harmondsworth: Penguin, 1939). This was followed less than a year later by the same two authors’ War Begins at Home, by Mass Observation (London: Chatto and Windus, 1940), which presented a portrait of public opinion and morale in Britain during the last third of 1939. A later work sampled the varieties of M-O's endeavours and revealed its considerable range in the field of social investigation: Angus Calder and Dorothy Sheridan, eds, Speak for Yourself: A Mass-Observation Anthology 1939–1949 (Oxford: Oxford University Press, 1985). Angus Calder also wrote a useful essay on ‘Mass-Observation 1937–1949’ in Martin Bulmer, ed., Essays on the History of British Sociological Research (Cambridge: Cambridge University Press, 1985), pp. 121–36.

M-O's invitation in August 1939 to its volunteer Observers to keep diaries was (we might say) an invitation to speak out – to give voice, perhaps, to one's own thoughts and feelings; to report on one's own experiences and contacts with others and incidents that would normally not be recorded; to put into words one's own perspective on ‘life’, whatever that might mean for a particular diarist. By the end of the war, around 480 people had written some form of diary for M-O. These diaries are impressively varied, as befits such a subjective genre. Some are almost entirely matter-of-fact; others are much more self-disclosing. Some are succinct, others long-winded; some are stylistically unremarkable, others reveal solid literary talent. Most diarists did not write for long – a few weeks, a few months, perhaps a year or so; the exigencies of living in wartime often got in the way of daily writing, which, at the best of times, is a habit that many people find hard to carry out. However, a few diarists kept at their work; they took it seriously, and commonly wrote a lot – and theirs are the diaries that are most likely to commend themselves for publication.