How to look for records of... Intelligence and security services
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1. Why use this guide?
This guide will help you to find records held at The National Archives of, and relating to, the British intelligence and security services.
The sensitive nature of intelligence work means that many files, especially those relating to living individuals or covering sensitive material, have been destroyed or retained by the security services themselves and have not been accessioned by The National Archives.
This guide does not cover records from police agencies such as the Special Branch. For advice on Special Branch records see our Metropolitan Police guide.
2. British intelligence agencies
The United Kingdom has several intelligence and security services, often referred to as the agencies. Historically, intelligence was gathered by individual branches of the military. But from 1909 onwards, separate intelligence agencies, operating alongside but independently of the military, have assumed increasingly important roles.
These are separate from police agencies such as the Special Branch or the Anti-Terrorist Branch (SO13) which have now merged to form Counter Terrorism Command (also known as SO15).
The Secret Intelligence Service (MI6) was founded in 1909 as the Foreign Section of the Secret Service Bureau and is responsible for gathering intelligence overseas. It is an agency of the Foreign and Commonwealth Office.
The Security Service (MI5) began in 1909 as the domestic arm of the Secret Service Bureau. It is responsible for protecting the country against threats to national security, which include terrorism, espionage and the proliferation of weapons of mass destruction. MI5 operates under the statutory authority of the Home Secretary, but it is not part of the Home Office.
The Government Communications Headquarters (GCHQ) began as the Government Code and Cypher School (GCCS) in 1919. It is responsible for providing signals intelligence for government and for the prevention and detection of serious crime. Ministerial responsibility for GCHQ lies with the Foreign Secretary.
MI5, MI6 and GCHQ work alongside each other and come under the direction of the Joint Intelligence Committee (JIC). The JIC sets the priorities and co-ordinates the work of the separate intelligence services. It comprises senior officials drawn from the Foreign Office, Ministry of Defence, Home Office, Department of Trade and Industry, Treasury and Cabinet Office, as well as the heads of the MI5, MI6 and GCHQ.
All these agencies work alongside the Ministry of Defence’s own Defence Intelligence Staff (DIS). Prior to the establishment of the DIS, each branch of the military had its own intelligence service (see sections 10, 11 and 12 of this guide).
3. Personnel records
In general, the identities of individuals who worked for the security and intelligence services are protected and therefore records of them are not made available to the public as freely as those from other branches of government. Records of individuals who are still alive usually remain confidential and are retained by the agencies themselves.
For more detailed information on records of individuals for a specific agency see the following sections of this guide.
4. How to search for records
The advice in this section will help you to make a start with your research. Consult the following sections of this guide for further search advice specific to the records of the individual agencies.
4.1 Online records
Only a few collections of intelligence records are available online. You can search within these collections by clicking on the links below and searching by keyword and date, unless otherwise indicated:
- Individuals monitored by the Security Service (MI5), the so-called Personal Files – search in KV 2 by name
- Reports and other papers from the Security Service (MI5) policy files, including the diaries of Guy Liddell 1939-1945, penned by the MI5’s Director of Counter-Espionage – search in KV 4 (not all KV 4 records are online; view a list of all online records in KV 4)
- Security Service (MI5) files, including lists of persons who fought in Spain 1936-1939 – search in KV 5 (not all KV 5 records are online; view a list of all online records in KV 5)
4.2 Original documents
Searches begin in our catalogue, which contains descriptions of each record alongside its document reference. You can search the catalogue using keywords and dates. Use the advanced search option to restrict your search results to records of a specific agency using the following department reference codes (click on the codes for accounts of the formation and history of each agency) for:
- The Security Service (MI5) – KV
- The Secret Intelligence Service (MI6) – HD
- Government Communications Headquarters (GCHQ) – HW
- Special Operations Executive (SOE) – HS
- Joint Intelligence Committee (JIC) – in CAB (records of Cabinet)
- Defence Intelligence Staff (DIS) – in DEFE (records of the Ministry of Defence)
You will also find intelligence records among those of other government departments, primarily:
- Foreign Office (for correspondence, policy and negotiation with other states) – FO and FCO
- Home Office – HO
Bear in mind that there may be overlap between different departments on any given subject or event. For example, a decision made during a conflict may have been informed by the Security Service (KV) and the Foreign Office (FO) and then discussed by the Cabinet (CAB) before being carried out by the Ministry of Defence (DEFE).
There is a very useful summary of source material on pages 277-279 of Twigge, Hampshire and Macklin’s British Intelligence (see Further reading).
5. MI5 and MI6 records
Access to records from MI5 and MI6 is restricted and many are not available publicly – this is especially true for MI6 files. The records are retained under section 3 (4) of the Public Records Act (1958) and Freedom of Information legislation does not apply to them. The National Archives policy on selecting records from the security services gives more information.
See section 4 for some basic advice on how to use our catalogue to search for records.
5.1 MI5 – The Security Service
Records of the Security Service, better known as MI5, are identified at The National Archives by the department reference KV. Some records have been deliberately destroyed whilst others were destroyed by bombing in 1940.
Records from the First and Second World Wars
A significant cross-section of Security Service records cover the World Wars. Among these are:
- Historical reports and policy files – in KV 4
- Second World War diaries of Captain Guy Liddell (head of MI5’s B Division, responsible for counter-subversion) – in KV 4/185-196
- Records of the London Reception Centre at the Royal Patriotic Schools – these files are scattered across KV 2 and KV 4 and are broken down in more detail in our guide to immigration records. The London Reception Centre was established to process aliens arriving in the UK, to gather intelligence from them on conditions in occupied Europe, and to screen arrivals for possible enemy agents.
Personal Files (PF): individuals monitored by the Security Service
These case files include records of suspected spies, renegades, communist sympathisers and right wing extremists. Search by name and download these records online (£) in KV 2.
PF numbers are sometimes found within files. These indicate there would have been a file opened but these files may not necessarily have survived or have been transferred to The National Archives.
Personnel files: individuals employed by the Security Service
It is not possible to get official confirmation of whether someone who is still alive worked for MI5.
If you believe that a deceased member of your family worked for MI5, you can write to the MI5 Enquiries Team to request information.
5.2 MI6 – The Secret Intelligence Service
Although department reference HD is for records of the Secret Intelligence Service, better known as MI6, there are, confusingly, no records generated by the agency held at The National Archives. The only records since 1909, when the agency was created, held in HD are of Polish military intelligence from 1946 and acquired by the agency. No transfers of records are expected in the foreseeable future.
There are archived versions of the MI6 website from 2006 onwards but otherwise the HD record series all pre-date the creation of the agency and are records inherited by rather than created by the agency.
However, reference is sometimes made to MI6 in files from other departments, such as in Foreign Office record series like FO 1093, which provides an illuminating account of the activities and funding of MI6. Search for “Secret Intelligence Service” or “MI6” in our catalogue to reveal some of the related material.
6. Joint Intelligence Committee records
Most records of the Joint Intelligence Committee (JIC) are among the records of the Cabinet, held in the CAB department, though there are some JIC reports held with the Foreign Office collection in FO. Of particular note are the following series:
7. Signals intelligence and code breaking: GCHQ and GCCS records
Signals intelligence – that is intelligence gathered by the interception of electronic signals as well as other means of communication – is, today, handled by the Government Communication Headquarters (GCHQ).
Records from GCHQ and its predecessor, the Government Code and Cypher School (GCCS), are identified in our catalogue by the department reference HW. The majority of the dozens of record series in HW cover the Second World War.
7.1 Basic searches
- signals intelligence
- code-breaking OR codebreaking
- cypher OR cipher
7.2 First World War records
There are very few HW record series covering solely First World War records but the following series are worth consulting for any study of First World War British intelligence:
- Correspondence, working papers and initial drafts of both official and unofficial histories of British signals intelligence in HW 3
- Official intelligence histories of the First World War written by senior Government Code and Cypher School members of staff in HW 7
7.3 Second World War records
There are dozens of record series in HW covering the Second World War.
In 1939 GCCS was moved to Bletchley Park and was renamed Government Communication Headquarters (GCHQ), also referred to as Station X or BP.
Use the advanced search option to restrict your search results to the HW department and search by keywords, such as:
- Bletchley Park OR Station X
- Enigma (the name of the German cypher system)
- BONIFACE (one of the code names used by GCCS)
- Bombe (the name of a machine used to help decode Enigma messages)
- Ultra (code name for signals intelligence)
8. Defence Intelligence Staff records
The Defence Intelligence Staff (DIS) is a branch of the Ministry of Defence (MOD). As such, its records are identified by the department reference DEFE, the reference for all MOD records held at The National Archives.
See section 4 for advice on how to use our catalogue to search for records across an entire department or target your search to one of the following series within the DEFE department. Click on the series references and search by subject keywords:
- Scientific and technical intelligence in DEFE 21 and DEFE 44
- Defence Intelligence Staff files in DEFE 31
- Intelligence assessments, reports and studies in DEFE 62, DEFE 63 or DEFE 64
- Reports and other papers from conferences and working parties in which the DIS participated, in DEFE 65
- Defence Intelligence Staff Sub-Committee minutes of meetings, correspondence and other files in DEFE 27
- Papers of R V Jones, the Director of Scientific Intelligence, 1939-1954 in DEFE 40
9. Special Operations Executive (SOE) records
Formed in 1940, the Special Operations Executive (SOE) functioned during the Second World War to promote sabotage and subversion and assist resistance groups in enemy occupied territory.
9.1 Personnel records
The records of SOE personnel are closed during the lifetime of the individuals or until their 100th birthday, when it is assumed they will have died. Where no date of birth is known the opening date of the records has been set at 2030, 100 years after 1930, the assumed birth year of the youngest agents in the field in the last year of the war.
Search the personnel files in HS 9 by first name, surname, year of birth or any combination of these.
If you are interested in a closed file and can demonstrate that the person it relates to is deceased, then you can submit a Freedom of Information request. If it relates to you personally you can make a request under Data Protection legislation using the ‘Data protection leaflet’ on our website.
You can also search the original SOE indexes in HS 11 to HS 20, which can list personal and biographical details of agents as well as contain references to the status of individuals who were known to be enemy intelligence officers, collaborators or traitors or who were in enemy hands or safe houses.
9.2 Other records
Read descriptions of the twenty record series which make up the records of the SOE in department HS. Click on the series references between HS 1 and HS 8 and in HS 10 to search that series by country name and/or subject keyword.
Records relating to SOE operations can also be found in the files of other departments, including the Air Ministry (AIR), War Office (WO), Foreign Office (FO) and Prime Minister’s Office (PREM).
10. British Army intelligence up to 1964
The War Office sections responsible for security and intelligence up until 1964 were the Directorate of Military Operations (DMO) and the Directorate of Military Intelligence (DMI). They were replaced in 1964 by the Defence Intelligence Staff (see section 8).
DMO was responsible for outline operational planning up to the time when an operation Commander was appointed. It also collected information about British forces and the armed forces of close allies.
The focus for DMI was the armed forces of enemy countries, distant allies and neutral countries. It was in close touch with military attaches and missions abroad and was interested not only in military details but also in more general historical, topographical and economic information.
The following record series are particularly useful for studies of:
- Late 19th century, First World War and inter-war years intelligence – WO 106
- First World War intelligence – WO 157 – this series contains daily “intelligence summaries”
- First World War intelligence maps – WO 153
- Second World War intelligence – WO 208
11. Naval intelligence up to 1964
The Naval Intelligence Department (NID), a branch of the Admiralty formed in 1886, provided much of the First World War and pre-First World War code-breaking expertise. The deciphering section formed in October 1914 was known as ‘Room 40’. NID was superceded in 1964 by the Defence Intelligence Staff (see section 8).
NID was concerned with all aspects of enemy and allied shipping including:
- plotting shipping movements, particularly of enemy surface cruisers and submarines
- collecting information on the topography of foreign countries, particularly coasts, and on coastal defences
The following record series are particularly useful for studies of:
- Pre-First World War intelligence – ADM 231 – includes printed NID reports on foreign naval strength, coastal defences and so on
- First World War naval intelligence – ADM 137 – includes papers of NID in ‘Room 40’, many of them on signals intelligence
- Second World War naval intelligence – ADM 223
- Second World War intelligence from intercepted German, Italian and Japanese radio communications – DEFE 3 – includes decrypted signals and summaries
12. Air Ministry intelligence up to 1964
The Air Ministry gathered intelligence on enemy aircraft, airfields and bombing targets as well as reports on the effectiveness of allied bombing raids (using aerial reconnaissance) and enemy and allied air activity in general. This work was carried out largely by the Air Intelligence Branch. In 1964 the separate intelligence services for each branch of the military were replaced by a unified service, the Defence Intelligence Staff (see section 8).
The following record series are particularly useful for studies of:
- First World War intelligence – AIR 1 – search for the numerous “intelligence summaries” and “intelligence reports”
- Second World War and the Air Ministry’s Directorate of Intelligence – AIR 40
- Second World War intelligence – AIR 24 – these are RAF Operations Record Books and they contain hundreds of intelligence reports – search simply for ‘intelligence’
- The Air Ministry’s Directorate of Operations and Intelligence and Directorate of Plans 1914-1947 in AIR 9 – search this series for reports and papers by the name of a country or region (for example, East Africa or Pacific), or subject keywords (for example, bombing or chemical warfare)
13. Records in other archives
Visit the webpages of the Consultative Group on Security and Intelligence Records for further help and guidance on intelligence-related records. This group is specifically set up to help the official, archival and academic communities with security and intelligence related material.
The British Library has a collection of intelligence material such as maps, plans and gazetteers on India and SE Asia.
14. Further reading
Consult the history section of the Secret Intelligence Service (MI6) website for information on the organisation’s history and records policy.
Browse the Security service (MI5) website for more information about the organisation.
Browse the history section of the Government Communications Headquarters website for more information about the organisation’s past.
The following books are all available in The National Archives’ reference library. Use our library catalogue to find a recommended book list. You can buy from a wide range of history titles in our bookshop.
Stephen Twigge, Edward Hampshire and Graham Macklin, British Intelligence (The National Archives, 2008)
Christopher Andrew, The Defence of The Realm: The Authorised History Of MI5 (Penguin, 2009)
Copies of the Intelligence and National Security journal are available at The National Archives’ Library. Issues of note include:
- ‘100 Years of British Intelligence’, Special Issue, Vol 27, Issue 1, 2012
- ‘Whitehall’s Black Chamber: British Cryptology and the Government Code and Cypher School, 1919-1929’, John Ferris, Vol 2 January 1987, pp.54-92
- ‘Declassification and Release Policies of the UK’s Intelligence Agencies’ and Sir Stephen Lander ‘British Intelligence in the Twentieth Century’, Vol 17 No 2, 2002, pp.7-32