‘A System Only to Be Defended on the Principle of Positive and Ascertained Necessity’: Quarantine and Thomas Maitland’s Contribution to the Medical Debates of 1819 and 1824

Summary This article focusses on the ‘plague debates’ which took place in the British parliament in 1819 and 1824, where the opinions of non-medical experts were also taken into account; particularly those of officials who had acquired relevant practical experience. Such opinions were crucial in politicising the medical debate from one of the nature of plagues, towards an evaluation of the impact of quarantine more broadly. Paying closer attention at the correspondence between the colonial governor of Malta and the Ionian Islands, and the colonial secretary, it reveals a different aspect of the contagion inquiry in Britain—one considering medical knowledge about plagues that was highly speculative. While most historical works illuminate the establishment of what was considered to be medical evidence, there is less work about the political, economic or even personal motives which underlined interventions in these debates.