In the immediate post-Second World War period, London's criminal cultures generated popular understandings of fantasy and cinematic escapism as a modern mode of life, a pleasure-seeking activity and a form of rationality. These narratives centred on increasingly visible but enigmatic genres of urban transgression: notably the phenomenon of spivery. Mixing petty crime, gambling and the black market with proletarian dandyism, urban waywardness and celebrity posturing, the cultural iconography of spivery was also associated with the deviant lifestyles of confidence tricksters, army deserters, good-time girls and mass murderers. Drawing on cinema, popular literature, courtroom drama, autobiography and psychiatry, this thesis explores how debates about the escapist mentalities of the spiv shaped the public discussions of crime as a socio-aesthetic practice. The central aim is to explore the cultural and symbolic associations between street-wise forms of deviant illusion and the cinematic representation of fantasising criminals in 1940s London. The thesis reveals how contemporary historical actors and cultural institutions understood the imagination as a popular and contested form of knowledge about the self, social change and erotic life. The method interweaves intertextual analysis of a key cinematic subgenre of crime, 'spiv films', with a historical focus on two 'true crime' stories: the cleft chin murder (1944) and the serial killings carried out by John George Haigh (1944-45). Utilising the criminals' self-confessions, trial transcripts, autobiography and popular journalism, these cases studies show how spivery was rooted in the experience and representation of everyday metropolitan life. The interdisciplinary examination of cinematic text and historical evidence emphasises how Hollywood aesthetics and indigenous national culture co-determined the public construction of 1940s crime as an embodiment of the contradictions of post-war British modernity.