This paper examines the New Survey of London Life and Labour, a social survey conducted within Greater London in the late 1920s and early 1930s. Relatively unknown compared to Charles Booth’s more famous survey of London some forty years before, the New Survey is perhaps the most detailed study of the lives of everyday Londoners in the inter-war period. This paper explains the background of the New Survey and examines the processes that were used to collect household information. It then examines how reliable the data is, especially given that doubts have been raised over the conduct of one interviewer in particular, who was responsible for collecting almost a fifth of the total information.