British government secret intelligence and foreign policy files from 1936 to 1953, with a focus on World War II. Sourced from the National Archives (UK) and available electronically for the first time.

Explore secret intelligence files from four key 20th-century conflicts—the Spanish Civil War, World War II, the early years of the Cold War, and the Korean War—with previously undigitized materials from The National Archives (UK).  Developed with a board of six experts, the material enables new research into intelligence, foreign policy, international relations, and military history.

At the heart of the collection are the files of the Permanent Undersecretary’s Department (PUSD), the point of liaison between the Foreign Office and the British intelligence establishment, documenting intelligence activities and its influence on foreign policy from 1873 to 1951, and providing new insights into key moments of 20th-century history through an intelligence lens.

Alongside eight other file series, including Cabinet Office papers and daily signals intelligence reports, The Secret Files enables day-by-day, in-depth study of war and a first look into how intelligence activities influenced the unfolding of events.

For research

For the first time, the full text of the files can be searched with keyword and proximity functionality. Hundreds of thousands of pages of critical materials can now be mined with sophisticated tools.

“Perhaps the greatest and most exciting British archival innovation in decades... a fascinating and a fantastic collection and ought to be the staple ingredient for all histories of the Second World War from now on.”

Professor Michael Goodman
Professor of Intelligence and International Affairs in the Department of War Studies, King’s College London

For learning

Students will be excited to engage with previously secret primary sources. Additional learning tools include:

• Specially commissioned subject essays written by members of the Editorial Board.

• A guide to organizations, committees, and subcommittees, including organizations within British intelligence, intelligence services of allied and hostile countries, and international organizations.

• A guide to the people—the key military, political, and intelligence figures in Britain and abroad who appear in the files and who played important roles in the events and operations discussed. The list provides a new route into the study of early 20th-century British intelligence, foreign policy, and international relations through some of the most significant personalities in these fields.

• For each of the nine-file series included, a description of the content, themes, and topics discussed has been provided by Dr. Stephen Twigge, Head of Modern Collections at The National Archives (UK).

Content Types

• Correspondence directives

• Financial reports

• Maps

• Meeting minutes

• Memoranda

• Reports

• Signals intelligence miscellany

“This collection represents some of the most valuable files from the British official archive on intelligence, defence and foreign policy... From students at many different levels working on their projects, to academic researchers with a specialist interest, there is an Aladdin's cave of secret history to be found here.”

Professor Matthew Jones,
Professor of International History at the London School of Economics and Political Science

CAB 56, 81, 158, 159, 176 Joint Intelligence Sub-Committee minutes and reports. 
A complete run of minutes and papers of the Joint Intelligence Sub-Committee from 1936 to 1953. The JIC assessed intelligence received from abroad and considered Britain’s intelligence and security priorities accordingly. Includes discussion on:

• The Spanish Civil War

• The growing threat and military power of Nazi Germany and the UK’s preparation for war

• Foreign espionage activities in the UK

• Key turning points of World War II

• World War II in Asia

• Hitler’s will and political testament

• Prisoners of war, including the interrogation of prisoners in the UK and the treatment of Allied prisoners in Germany

• Assessments of enemy weapons development, including German secret weapons

• The threat of war with the Soviet Union during the early Cold War and assessments of Soviet military capabilities and intentions

• Developments in the Middle East (1946-1968), including the partition of Palestine and anti-British insurgence

• The spread of communism in East Asia and the Chinese Civil War

• The Korean War and British, U.S. and Chinese involvement

• Scientific intelligence, including intelligence on atomic energy, atomic weapons, and biological warfare

• Defectors and deserters from the U.S.S.R. and their exploitation for intelligence

• Intelligence gathering in and reports on countries around the world

FO 1093 Foreign Office: Permanent Under- Secretary’s Department: Registered and Unregistered Papers, 1873–1985.  
Files on intelligence, military operations, foreign policy, and defense concerns, in which information was gathered by covert means. Includes:

• Papers relating to the wartime imprisonment of Rudolf Hess

• UK-Soviet wartime relations

• Discussion of proposed assassination targets ahead of Operation Overlord

• Defection to Canada of Soviet agent Igor Gouzenko

• HW 1 Government Code and Cypher School: Signals Intelligence Passed to the Prime Minister, Messages and Correspondence, 1940 –1945

• Thousands of signals intelligence reports issued by the Government Code and Cypher School and sent to Winston Churchill several times each day during World War II, with associated correspondence and annotations. It includes intelligence from ENIGMA signals and covers all aspects of the Allied military campaign against Germany, Italy, and Japan.

CAB 301 Cabinet Office: Cabinet Secretary’s Miscellaneous Papers, 1936 –1952

A collection of confidential papers on intelligence matters originating from the Private Office of the Cabinet Secretary. The papers relate to the organization, role, and funding of the intelligence services, as well as signals intelligence and code-breaking. Includes:

• The funding of MI5 and MI6 activities

• The organization and responsibilities of British intelligence

• The Special Operations Executive

• Commonwealth defense and the security of British missions overseas

CAB 163 War Cabinet, Ministry of Defence, and Cabinet Office: Central Intelligence Machinery: Joint Intelligence Sub-Committee, later Committee: Secretariat: Files, 1939 –1985. 
A miscellaneous collection of papers that allow for an analysis of case studies of operations, events, and intelligence concerns during and after World War II. It includes:

• Papers on security and intelligence planning and threats relating to Operation Torch

• Winston Churchill’s miscellaneous correspondence

• Sir Douglas Evill’s 1947 report on the UK’s intelligence services
  

Access Options

The file is currently available as a one-time purchase of perpetual rights or through annual subscription on the History Commons platform with new features including:

• Ability to cross-search across all the history collections, with additional discovery tools

• Updated, faster user interfaces, with mobile versions

• Enhanced indexing

• Search tables hidden within documents and export the data

• Enhanced search tools, including Boolean and proximity operators

• Free hosting of your related content