‘It Must End, or I Must End’: Castlereagh, Mental Health and Politics in Regency Britain

Abstract Viscount Castlereagh (1769–1822), Britain's polarising foreign secretary and leader of the house of commons from 1812–22, has been studied through the lens of diplomacy and politics, but never through the lens of mental health. As 2022 marked the 200th anniversary of Castlereagh's suicide, mental health is still the missing link in our understanding of both Castlereagh as a public and private figure and the politics of his era. This article examines Castlereagh's career through the lens of modern research on mental health, applying an interdisciplinary approach that combines history, psychology, sociology, political studies and gender studies. The article argues that applying a mental health lens helps us better understand the pressures on Castlereagh as a politician, the stresses and strains of Regency‐era politics, and how those stresses resulted in risks to mental health. Perhaps most importantly, the article concludes that Castlereagh continues to be relevant today because his story illustrates: first, the need to understand the complexity of mental health risks in politics; and second, the types of persistent mental health risks that are still relevant for today's politicians and civil servants.