We are often asked questions about our work and how we operate. This section provides answers to frequently asked questions and tackles some of the most common myths about MI5.
Yes. MI5 is a government department under the authority of the Secretary of State - in practice the Home Secretary.
This has always been the case. Our functions are, however, set out by Parliament in the Security Service Act 1989 and we can only act in the pursuit of those functions.
The UK's two other intelligence agencies (SIS and GCHQ) have a similar status, but they’re under the authority of the Foreign Secretary.
We don’t formulate or implement government policy but we do advise government departments and the Prime Minister about the current threats to national security. We also provide advice to government organisations on protective security measures.
The Security Service Act 1989 requires our Director General to ensure that MI5 is apolitical. The government can’t instruct us to do something for party political reasons.
The name dates back to the First World War. For part of the war, MI5 was the fifth branch of the Directorate of Military Intelligence of the War Office (the predecessor of today's Ministry of Defence).
A number of other "MI" branches existed within this directorate (see the FAQ "What happened to MI1 - MI4?"). They were later discontinued or absorbed into other organisations, with the exception of our colleagues in SIS (MI6).
MI5 was renamed to the Security Service in 1931 when it merged with Scotland Yard's Special Section, which had similar responsibilities for domestic intelligence. We’re no longer part of the UK military establishment, although we do still contribute - along with the military - to the overall national security of the UK. We still use the name "MI5" as shorthand for our official name, the Security Service.
See What's in a Name? for more details.
MI5 was founded as the Home Section of the Secret Service Bureau. It was part of the War Office in the First World War, between 1916 and 1918. During this time it was renamed MI5, referring to its status as the fifth branch of the Directorate of Military Intelligence (see the FAQ "Where does the name "MI5" come from and why is this name still used?"). In the Second World War, MI5 was independent of the War Office, though it worked closely with it.
There were a number of MI (Military Intelligence) sections within the War Office's Directorate of Military Intelligence during both the First and Second World Wars. There were eventually ten MI sections during the First World War and seventeen by the end of the Second World War. The number of MI sections and their precise functions varied considerably as the demands of the war effort changed.
Few had anything to do with secret intelligence. For instance, MI4 during the First World War was responsible for supplying military maps, while MI9 during the Second World War helped Allied troops to evade and escape from behind enemy lines.
All of these sections, with the exception of our colleagues in the SIS (MI6), were later discontinued or absorbed into other organisations.
In October 1909, Captain Vernon Kell of the South Staffordshire Regiment and Captain Mansfield Cumming of the Royal Navy jointly established the Secret Service Bureau following a recommendation by the Committee of Imperial Defence, which had been considering the danger from German espionage.
To meet an additional requirement from the Admiralty for information about Germany's new navy, Kell and Cumming decided to divide up their work. Thereafter, Kell, or "K", was responsible for counter-espionage within the British Isles while Cumming, or "C", had responsibility for gathering intelligence overseas. The two divisions became MI5 and MI6 respectively.
While the head of MI6 (SIS) is still referred to as "C" today, the Director General of MI5 has not been known as "K" since the 1940s.
See The establishment of the Secret Service Bureau for the full story of how MI5 was founded.
The MI5 crest
The MI5 crest was designed by the late Rodney Dennys, the Somerset Herald of Arms. It was adopted in 1981 with the approval of the Garter Principal King of Arms. It also appears on MI5's official flag with the approval of Her Majesty the Queen.
At the centre of the crest is a golden winged sea-lion on a blue background. This is not to be confused with the real sea lion (a type of seal) but is a mythological beast, half-lion and half-fish. It represents our historical association with the three armed services. The lion's head stands for the Army, the fish's body for the Royal Navy, and the wings for the Royal Air Force. Gold traditionally represents virtue. The colour blue in the background signifies our overseas ties.
Surrounding this central emblem are three further symbols: a green cinquefoil (a leaf with five petals), a portcullis and a red rose.
- The cinquefoil's five petals allude to the "5" in MI5. The colour green has been associated with intelligence since the First World War.
- The portcullis, traditionally a symbol of parliament, relates to MI5's key task of upholding parliamentary democracy. The crown at the top of the uppermost portcullis refers to the Crown, the legal embodiment of the State.
- The rose has historical associations with state intelligence work. Sir Francis Walsingham, Queen Elizabeth I's spymaster in the 16th century, used it on his seal. He is widely regarded as the first intelligence chief in British history. The rose's five-lobed petals are another allusion to the "5" in MI5.
At the bottom of the crest is our motto: "Regnum Defende", meaning "Defend the Realm" in Latin. This refers to a directive issued in 1952 by the then Home Secretary, Sir David Maxwell-Fyfe. It defined MI5's mission as being "the Defence of the Realm as a whole" from threats to national security such as espionage, sabotage and subversion.
We currently employ about 4,400 people. 43% of our employees are women, just over half are less than 40 years old, 9% are from black or ethnic minority backgrounds and 4% have a disability.
For security reasons, we don't offer public tours of our headquarters, Thames House.
Although MI5 is often described as the UK's "domestic" intelligence service, our operations aren’t purely domestic. Threats to the UK's national security often come from overseas. For instance, foreign intelligence services and international terrorist groups seek to target UK interests at home and abroad.
We’ll work outside the UK where it’s necessary to protect the UK's national security or to counter security threats to UK interests such as diplomatic premises and staff, UK companies and investments, and our citizens living or travelling abroad.
Dealing with these threats, wherever they arise, falls within the scope of our functions as set out in the Security Service Act 1989. We work closely with other UK agencies and organisations that are involved in dealing with overseas threats to the UK.
We have a close working relationship with our sister UK intelligence agencies, SIS and GCHQ, who are responsible for gathering foreign intelligence.
We co-ordinate our activity with the Foreign and Commonwealth Office, which provides travel advice on security threats to UK citizens abroad. We also have a number of partnerships with overseas police forces and intelligence agencies.
MI5 isn’t a secret police force and our staff don’t have the power to detain or arrest people. We’re a publicly accountable civilian intelligence organisation, not a law enforcement agency.
We work closely with the police and other law enforcement agencies to help them bring to justice people who are committing or planning crimes. The intelligence that we produce can often be admitted as evidence in criminal trials. Special procedures are in place for handling intelligence evidence and disclosures.
Our role is defined in law by the Security Service Act 1989. This limits our responsibility to protecting the UK against threats to national security from espionage, terrorism and sabotage, from the activities of agents of foreign powers, and from actions intended to overthrow or undermine parliamentary democracy by political, industrial or violent means. The law also prohibits us from acting to further the interests of any political party.
We’re accountable to ministers, parliament and senior judges who serve as commissioners and provide external scrutiny. Parliament's Intelligence and Security Committee regularly publishes reports on our work.
Yes. The Security Service Act 1989 requires the Director General to produce an annual report for the Prime Minister and the Home Secretary.
The report is not published for security reasons, as it contains sensitive information on the work of MI5. No version is made available to the public.
However, the independent oversight commissioners and the Intelligence and Security Committee publish their own reports on MI5's work (see Law and governance).
The Director General receives many invitations to speak at a variety of public events. Unfortunately, pressure on his diary means he has to turn down the vast majority.
We can’t confirm whether someone who is still alive worked for MI5. We maintain the confidentiality of our staff members' employment throughout their lifetimes to avoid endangering them or the people they worked with.
If you believe that a deceased member of your family worked for MI5, you can write to us at:
The Enquiries Team
PO Box 3255
Please be aware that written correspondence posted in the UK may take up to a week to reach us.
Please give details of your relative (ideally the full name and date of birth), include a copy of their death certificate and state the purpose of your enquiry. We’ll then consider all the circumstances of the case and what if any information may be released.
No. Sir Roger Hollis, the Director General of MI5 from 1956-1966, was investigated after allegations were made that either he or his deputy, Graham Mitchell, fitted the profile of a long-term undercover Soviet agent. The allegations were made following the exposure of the Cambridge spy ring and the subsequent hunt for other Soviet moles.
The investigation lasted from 1964 to 1971 but came to no firm conclusions. The affair was reviewed in 1975 by Lord Trend, a former Cabinet Secretary, who found that there was no evidence to show that either Hollis or Mitchell had been Soviet agents.
An internal review carried out within MI5 in 1988 was strongly critical of the original investigation, concluding that the case against Hollis and Mitchell was "so insubstantial that it should not have been pursued".
Hollis' non-involvement with the Soviets was confirmed in the 1980s by a senior KGB defector, Oleg Gordievsky. He has described how the Soviets themselves were baffled by the allegations against Hollis and attributed them to "some mysterious, internal British intrigue".
MI5 and MI6 (SIS, the Secret Intelligence Service) are both intelligence agencies, but they do different things. The following provides a brief summary:
- MI5 is responsible for protecting the UK, its citizens and interests, at home and overseas, against threats to national security.
- SIS is responsible for gathering intelligence outside the UK in support of the government's security, defence, foreign and economic policies.
- MI5 is headed by Ken McCallum (see Director General).
- SIS is headed by Alex Younger.
- MI5 is answerable to the Home Secretary (see Law and governance).
- SIS is answerable to the Foreign Secretary.
- MI5’s headquarters are at Thames House, London.
- SIS’ headquarters are at Vauxhall Cross, London.
MI5's work has been depicted in a number of films and TV series, notably the BBC's "Spooks" ("MI-5" in the United States). Such works of spy fiction glamorise the world of intelligence and, although they’re entertaining, they tend not to be very realistic.
Our work can certainly be stimulating and highly rewarding. However, in real life a large percentage of our work is routine and painstaking (though vitally important) and wouldn’t be at all entertaining to watch. More importantly, unlike our fictional counterparts we work within the law. All of our operations are carried out within a legal framework and with careful risk management and oversight.
See Working at MI5 to find out more about what it’s really like to work here.
We don’t investigate any group or individual on the grounds of their ethnicity or religious beliefs. MI5 is committed to protecting the security of all of the UK's citizens, of every faith and ethnic group. We only carry out investigations if there is a clear national security reason for doing so.
Some international terrorist groups support an extreme interpretation of Islam that is widely rejected by ordinary Muslims and Islamic scholars. They have been responsible for many terrorist attacks around the world. MI5's largest single area of work is the effort to counter such extremist terrorist groups.
Al Qaida, the Islamic State of Iraq and the Levant (ISIL) and similar groups are often indiscriminate when carrying out attacks. Muslims are often themselves the victims of violence carried out by terrorists who claim to be acting in the name of Islam.
We employ staff of all religions, including Muslims. We are committed to recruiting a diverse range of staff from all backgrounds. This enables us to benefit from their different perspectives and experience. See Languages for information about employment opportunities for British citizens who speak other languages.
MI5 doesn’t have any responsibility for the general vetting of candidates for public sector employment.
The Security Service Act 1989 imposes strict controls on how we may use or disclose information on individuals. We can only disclose information to assist employment decisions if we do so in accordance with arrangements approved by the Home Secretary.
The provisions mentioned in the Act mean we play a part in vetting candidates for sensitive government posts. However, our role is confined solely to checking our records.
If when we check we find that we have a significant and relevant security record on an applicant, we may provide a summary assessment of the security information. However, the mere existence of an MI5 record does not necessarily mean that an assessment will be made.
There is no "blacklist" and decisions on employing staff are the responsibility of the department concerned. We don’t investigate or interview candidates on their behalf.
For more information on how vetting is used in government, see HMG Personnel Security Controls.
Ministers and MPs are not subject to vetting.
We’ll tell an incoming Prime Minister about any information we hold on a potential member of the new Cabinet only if that information raises serious national security concerns and only if it appears likely that the individual concerned will need access to sensitive information.
A similar arrangement has been in operation for the Official Opposition since 1992. The Leader of the Opposition is briefed on any serious security issue concerning a possible member of the Shadow Cabinet. This is necessary because members of the Shadow Cabinet are often briefed on security issues.
These arrangements have only ever been used on a very small number of occasions since MI5 was established over a hundred years ago.
MI5 does not normally investigate leaks or lost data. The exception is where national security may have been affected.
The Centre for the Protection of National Infrastructure (CPNI) will conduct an audit of security plans within other government departments on request. It also gives security advice to government departments and other organisations responsible for critical national infrastructure.
However, the CPNI and MI5 don’t have any role in policing the security of government departments. It is the responsibility of each department to ensure that their data is handled securely and that any loss of data is investigated, possibly involving the police if required.
MI5 doesn’t routinely monitor the private lives of prominent people and never simply because of their high profile. We will only carry out an investigation if there’s a clear national security reason for doing so.
Our investigations are limited by the Security Service Act 1989 to protecting the UK's national security and economic well-being.
In the past we have occasionally investigated public figures where there have been concerns that they may have been involved in issues of concern to national security. Files relating to some historical cases have been released to The National Archives. See MI5 at The National Archives for more information.
MI5 has from time to time been accused of systematically investigating trade unions and pressure groups such as the National Union of Mineworkers and the Campaign for Nuclear Disarmament.
We have never investigated people simply because they were involved with trade unions or campaigning organisations. The Security Service Act 1989 requires us to be politically neutral and not act for the benefit of any political party. We only investigate matters that affect national security, within the remit set out in the Act.
In the past, subversion was seen as a significant threat. In a 1975 House of Lords debate, the then Home Office Minister Lord Harris of Greenwich defined subversive activities as those "which threaten the safety or well-being of the state and which are intended to overthrow or undermine parliamentary democracy by political, industrial or violent means."
As the then Home Secretary Douglas Hurd later put it, "the sole criterion in relation to a subversive threat is whether there is a deliberate intention to undermine parliamentary democracy and whether that presents a real threat to the security of the nation." The Security Service Act 1989 gave this criterion the force of law.
Some subversive groups sought to infiltrate and manipulate other organisations as a way of exerting political influence. This was a particular concern during the Cold War and before, when there were fears that mainstream organisations were being used as front groups or were being infiltrated by the far left and far right for anti-democratic purposes.
To meet our responsibility for protecting national security, we investigated individual members of bona fide organisations where there were grounds to believe that a genuine subversive threat existed. We investigated the activities of subversive groups but not the organisations they sought to penetrate. Such investigations were carried out within the laws and processes that applied at the time.
The threat of subversion is now regarded as negligible and we do not currently carry out investigations in this area. A number of files on historical cases concerning suspected subversive activity have been released to The National Archives, where the public can view them (see MI5 at The National Archives).
Terrorism is the biggest national security threat that the UK currently faces. Our highest priority is the threat of international terrorism. Terrorist organisations based in Northern Ireland also continue to pose a serious threat.
Espionage (including cyber espionage) from foreign states is still a significant problem. Despite the end of the Cold War, at least 20 foreign intelligence services are still actively operating against UK interests. Russian and Chinese intelligence activities are an ongoing concern.
The proliferation of weapons of mass destruction (WMD) also continues to pose a threat to international peace and stability. Several countries are actively pursuing WMD programmes and have sought to illicitly obtain equipment and expertise from the UK.
The statutory basis under which MI5 operates authorises us to investigate subversion and serious crime. However, we no longer investigate either of these issues. Subversion is no longer seen as a significant threat and countering serious crime is now the responsibility of the National Crime Agency (NCA).
The current UK threat level for international terrorism is SUBSTANTIAL, meaning an attack is likely.
The current threat level for Northern Ireland-related terrorism is SEVERE in Northern Ireland (an attack is highly likely) and MODERATE in Great Britain (an attack is possible, but not likely).
For more information, see Threat levels.
There are a number of organisations that provide advice on how to protect against terrorism and other threats. To find out more, see What you can do.
If you know something that you think would help us in countering national security threats like terrorism or espionage, please get in touch (see contact us). Please note that we can’t help with issues that don’t relate to national security.
We only investigate individuals whose activities relate to threats to the UK's national security, which the Security Service Act 1989 defines as:
- espionage, terrorism and sabotage;
- the activities of agents of foreign powers;
- actions intended to overthrow or undermine parliamentary democracy by political, industrial or violent means (subversion);
- serious crime (though we have suspended investigative activity in this area since 2006).
Unless you’ve been involved with such a threat it is very unlikely that we’d ever have had any interest in you.
The Data Protection Act 1998 (DPA) gives individuals the right to apply for access to personal data relating to them. This is known as a "subject access request". However, under the exemption provision in section 28 of the DPA, requests for information may be declined in cases where it is necessary to safeguard national security.
Subject access requests should be made in writing and a fee will be charged. MI5's Data Controller considers on a case by case basis whether exemption from the access provisions is required and justified on the grounds of national security.
Members of the public who are not satisfied with a reply to a subject access request may appeal to the Information Tribunal (see Access to information).
MI5 only investigates individuals whose activities fall within the remit set out in the Security Service Act 1989.
If you believe you have been the subject of improper enquiries or other actions by MI5, you can complain to the Investigatory Powers Tribunal. This independent Tribunal considers complaints relating to the activities covered by the Regulation of Investigatory Powers Act 2000, and also hears proceedings brought under the Human Rights Act 1998.
The address of the Investigatory Powers Tribunal is:
PO Box 33220
We don’t tap telephones or install eavesdropping equipment illegally.
Our intelligence gathering methods are governed by the Regulation of Investigatory Powers Act 2000. This requires us to get permission from the Secretary of State - in practice, the Home Secretary - to allow us to use intrusive investigative methods.
Where an eavesdropping operation would also involve our officers entering or interfering with a property, a separate warrant has to be obtained under the Intelligence Services Act 1994.
In all cases, a rigorous process is carried out within MI5 to ensure that any application for a warrant is both necessary and justified.
Our use of these intrusive powers is subject to oversight by two independent commissioners. The Interception of Communications Commissioner and the Intelligence Services Commissioner check that we are using these powers correctly.
An agent, or Covert Human Intelligence Source, is someone who works for us to obtain secret intelligence. They’re one of our most important sources of intelligence. Agents are not employed by MI5 and there is no formal application process to become an agent.
Agent operations, run strictly in accordance with the relevant legislation, are handled by specially trained MI5 officers. The safety of our agents and their families is always paramount.
If you know something specific about a threat to national security, we would like to hear from you. You can send us your information in confidence via the Contact us page of this website (an alternative telephone number and address are also provided).
If you would like us to get in touch with you, please also include your contact details.
Although our members of staff are often erroneously described as "agents", we refer to them as officers. Vacancies for new officers are publicly advertised through this website - see Careers for more information on what jobs are currently available and how you can apply for them.
There’s no such thing as "a typical MI5 officer".
We seek to recruit from all areas of the UK and all sections of society. Our staff members come from a wide range of backgrounds and cultures, reflecting the diversity of the communities in the UK that we serve.
MI5 is an equal opportunities employer. 43% of our staff are women and just over half of our staff are under the age of 40. An increasing number of staff members (currently around 9%) are from black or ethnic minority backgrounds, and 4% have a disability.
See Careers for more information about our current vacancies and working at MI5.
Yes. MI5 takes the welfare of its staff very seriously.
We work to ensure that our staff have a healthy work/life balance with reasonable working hours. Most roles provide a wide range of flexible working arrangements, including flexi-time, job-sharing and compressed hours.
We offer generous maternity and paternity leave. There is a strong support network within MI5 to provide advice and assistance for our staff.
For more information, please see Careers.
If you’ve started an online application that you want to re-visit, see Access my application.
If you’re having problems with the careers part of our website, please contact our recruitment team on 0845 450 2152 or at [email protected]. If your enquiry is urgent then please ring the recruitment team.
We currently employ about 4,400 people. More than 43% of staff are women, the average age of our employees is 39, over 9% are from black or ethnic minority backgrounds and 4% have a disability.
MI5 deals with very sensitive information. Lives may be put at risk if sensitive information is disclosed carelessly. This makes it vital to manage information properly and release it only when absolutely necessary.
Section 1 of the Official Secrets Act 1989 prohibits our current and former staff from making unauthorised disclosures of information concerning security or intelligence that they acquired while working for MI5. We can only pass on information as is necessary for purposes of protecting national security.
The Official Secrets Act does not prohibit disclosures of unimportant matters. However, we advise our staff to be aware of the sensitivities and potential risks when discussing their involvement with or knowledge of MI5.
Latest NewsView all news
MI5 Director General Ken McCallum gave his annual threat update at Thames House on 14 July 2021.