The study of intelligence history has seen considerable growth over the last 20 years, as a result of new archival evidence and above all a growing realisation that intelligence has for long been the "missing dimension" in historical interpretation of 20th century diplomacy, defence policy and strategy and in the operational history of two world wars. A consideration of the impact of intelligence assessment, its acceptance (or rejection) and its proponents has well known areas of historical analysis, particularly in the period from the 1930s to the Cold War. The aim of this module is to examine the current historiography of this "missing dimension" and assess its impact in the interpretation of British strategic and defence policy and to some extent, in internal and imperial security as well as considering popular and fictional interpretations of the intelligence service.