Before being awarded a research post at Swansea, Theresa completed her PhD at the University of Nottingham (School of History). Her research work was a continuation of both her undergraduate degree in French Language and Culture and MA (by research) in History. Her study of plant nomenclature in Romance languages was a revelation and, together with her research in the history of medicine, suggested the existence of medical knowledge which had crossed both language and geographical boundaries. This led her to question the origins and authorship of the knowledge embedded in medieval medical texts and the motivation for their production. Her doctoral dissertation included research of a wide range of codices which were produced during the period c.1200 and 1500 and focussed on the changes that had taken place during the transmission from their Latin source text into the vernacular. As this focus was on the fertility advice they contained it naturally led to an examination of the society in which they were produced and their ownership in the late-medieval period together with their fortunes following the Reformation. Her interest in healing and health, and the practicalities of obtaining the plants used in medicine and healthcare, has led her to extend this research to other types of manuscripts containing health advice, such as those produced for domestic use including Livres de Raison and personal journals.