Poppy is a historian of decolonization and post-colonial relationships between Britain and Africa. She is interested in the transition from colonial to independent states in the 1960s and how organizations and individuals in a variety of fields – military, political, economic, humanitarian – adapted to this transition.

Her book 'Kenya and Britain after Independence Beyond Neo-Colonialism' focused on the political relationship between Britain and Kenya in the decades after independence, the 1960s to 1980s. She examined how political elites in both countries re-thought their relationships after Kenyan independence, and how the different forms of diplomacy practiced by the two states shaped the foreign policies they followed. She argued that British diplomats encouraged personalized rather than bureaucratic policymaking in Kenya. At the same time, they naturalized this kind of personalized politics, often termed neo-patrimonialism, as something inherently ‘African’. Poppy has published on various aspects of Anglo-Kenyan relations in a number of journals.

Her current research is focused on two areas. Firstly, military decolonization and Africanization in East Africa. Here, Poppy explores the precarious transformation of colonial armies intended to secure imperial rule to independent African militaries. Secondly, the history of humanitarianism and NGOs in Africa during the period of decolonization. This includes work on ‘The Big Survey’ of NGOs carried out in the 1960s, and research into the Mau Mau Emergency.