If the colonial ‘other’, as Edward Said so eloquently showed, was as much invented or imagined as honestly appraised then the same might also be said of the colonising self. Whilst the supposed backwardness of subject races served to legitimate colonial rule, so, equally, did the totemic figure of the masterful European. As recent work has shown, however, colonial populations were never as stable or as homogenous as was once believed: a significant number of ‘poor whites’ - in Southern Africa, India, the Dutch East Indies and elsewhere - challenged the prestige of the ruling race. To speak of ‘poor whites’, however, itself a term of colonial discourse, risks reinforcing the exceptionality that the term implies. Taking Kenya as a case study, this thesis seeks to get beyond the archetypes conferred by both the ‘poor white’ and the masterful European. To do so, I argue, it is necessary to seek out those who have themselves been marginalised or forgotten. To this end, the thesis uses case files of European patients treated at the Mathari Mental Hospital in Nairobi, alongside records pertaining to European welfare and the deportation of ‘undesirables’, to construct a social history of mental illness and social marginality in Britain’s supposedly most aristocratic colonial possession. The resulting study not only shows up the diversity and disorder of Kenya’s colonial Europeans but also opens up new avenues for rethinking the nature of their interior, lived experience. Doing so, I argue, makes possible a recognition of the Europeans in Kenya not as agents of power but as sentient, susceptible human beings.