This paper examines how modern economic statecraft was developed in the early 20th Century, and how a better understanding of that history might improve policy making today. It is meant to serve as a concise and accessible history for practitioners. Plenty has and is being written on the policy of economic statecraft; this paper seeks to illuminate the lessons for its practice. How it was bureaucratically conceived, developed, contested, refined, professionalised and eventually discarded. It draws heavily on existing scholarship, including Nicholas Lambert’s essential work on the pre-war period, Planning Armageddon, and it attempts to fill later gaps in the literature through primary research at the UK’s National Archives.