MI5 vs MI6: Difference and Comparison

The term “intelligence agencies” stands for a government department responsible for collecting information related to military or politics in support of national security. 

When it comes to the UK, MI5 and MI6 are both intelligence agencies. Still, they are different from each other because MI5 is the British security service whereas MI6 is the British foreign intelligence service. 

Key Takeaways

  1. MI5 focuses on domestic security and counterterrorism within the United Kingdom, while MI6 deals with intelligence gathering and operations abroad.
  2. MI5’s full name is the Security Service, whereas MI6 is formally known as the Secret Intelligence Service (SIS).
  3. MI5 operates under the authority of the Home Office, while MI6 falls under the jurisdiction of the Foreign and Commonwealth Office.

MI5 vs MI6 

MI5 is the domestic intelligence agency responsible for national security and counterintelligence within the UK. Its main role is to protect the country from threats such as terrorism, espionage, and cyber-attacks. MI6 is the UK’s foreign intelligence agency responsible for gathering intelligence from overseas sources to protect national security and promote UK interests abroad.

MI5 vs MI6

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MI5 is derived from the Secret Service Bureau and completed 111 years in 2020. Its main motto is to keep the country safe regarding national security.

The Agency executive Andrew Parker (2013-2020) was succeeded by Ken McCallum (Director General). It’s licensed to investigate any person or movement regarding an internal threat. 

MI6 is the foreign section of the Secret Service Bureau and completed 112 years in 2021. The target of MI6 is to work overseas to make the UK safer and more prosperous.

The Agency executive Alex Younger (2014-2020) was succeeded by Richard Moore (Chief). Most of the staff of Mi6 are based overseas, and others work from MI6 headquarters in Vauxhall, London.

MI6 is authorized by senior government ministers and supervised by Parliament. 

Comparison Table

Parameters of ComparisonMI5MI6
FounderVernon KellH.H. Asquith
EstablishedOct1909July 1909
Headed byKen McCallumRichard Moore
HeadquarterThame House, LondonVauxhall Cross, London
Employees 4,400 people2,594 people (31 march 2016)

Brief History and Establishment

This table provides an overview of the key historical milestones and the establishment of both agencies.

Parameter of ComparisonMI5MI6
Original NameSecret Service Bureau (Domestic Section)Secret Service Bureau (Foreign Section)
First Director-GeneralVernon KellMansfield Cumming
Initial PurposeCounter-espionage within the British EmpireForeign intelligence and counter-espionage outside the UK
HeadquartersThames House, London, EnglandVauxhall Cross, London, England

Key Responsibilities and Tasks

This table outlines the major roles and responsibilities of MI5 and MI6.

Parameter of ComparisonMI5MI6
Primary RoleDomestic IntelligenceForeign Intelligence
Key ResponsibilitiesCounter-terrorism, Counter-espionage, Protecting UK’s EconomyGathering foreign intelligence, Safeguarding UK’s national security interests
Security FocusInternal SecurityExternal Security
Target ThreatsTerrorism, Espionage, CybercrimeInternational terrorism, Arms proliferation, Organized crime
Key ActivitiesSurveillance, Investigation, ProtectionEspionage, Covert operations, Liaison with foreign agencies

Jurisdiction and Operational Scope

This table highlights the operational scope and jurisdiction of both agencies.

Parameter of ComparisonMI5MI6
JurisdictionUnited KingdomWorldwide
Operates inMainly within the UKMainly outside the UK
Legal AuthoritySecurity Service Act 1989Intelligence Services Act 1994
Oversight BodyInvestigatory Powers TribunalIntelligence and Security Committee

Leadership Structure

This table describes the leadership structure of MI5 and MI6.

Parameter of ComparisonMI5MI6
Head TitleDirector-GeneralChief of the Secret Intelligence Service
AppointmentAppointed by the Home SecretaryAppointed by the Foreign Secretary
Reports toHome SecretaryForeign Secretary
TenureNo fixed termNo fixed term

Famous Operations and Cases

This table lists some of the most famous cases and operations handled by both agencies.

Parameter of ComparisonMI5MI6
Famous CasesThe Cambridge Spy RingOperation James Bond
The Portland Spy RingOperation Gold
The Spycatcher AffairOperation Embarrass
The Mitrokhin ArchiveThe Penkovsky Papers
The Illegals Program (Anna Chapman Spy Ring)Operation Stopwatch/Goldeneye

What is MI5? 

MI5(Military Intelligence, Section 5), formally known as the security service, mainly deals with internal threats. It is directed by the Joint Intelligence Committee, whose main priority is to conduct intelligence operations.  

MI5 aims to protect the UK as a whole against threats to national security.

MI5 counters terrorism (who use violence to publicize their causes), espionage (who seek UK information), cyber (several hostile actors targeting the UK), and proliferation (developing weapons of mass destruction). 

It is headed by a Director General (DG) supported by the secretariat, internal security organization, information services branch, and legal advisory branch. Captain Vernon Kell founded it in October 1909.

He was the Major General then and played an important role at the start of World War I as he captured most of imperial Germany’s intelligence.  

Captain Vernon Kell was also known as “K”. As a result, whoever was appointed as the Director-General of MI5 was known as “K” until the 1940s. 

At the time of the First World War, MI5 was the fifth branch of the Directorate of Military Intelligence, as the name suggests MI5(Military Intelligence, Section 5) of the war office.

At that time, several other “MI” branches existed within this directorate but were later discontinued, except SIS(MI6). 

MI5 Structure

MI5, also known as the Security Service, is the United Kingdom’s domestic counter-intelligence and security agency. It operates under the direction of the Joint Intelligence Committee (JIC) and protects national security within the UK. The head of MI5 is known as the Director General.

The organization is structured into various branches, each focusing on a specific area of intelligence and security. Some key divisions within MI5 include:

  • Counter-Terrorism: This division deals with threats posed by terrorist organizations to the UK.
  • Counter-Intelligence: This branch identifies and neutralises foreign intelligence threats within the UK.
  • Protective Security: This department handles securing government infrastructure and vital assets.

MI5 Operations

As a reader interested in intelligence agencies, you would want to know that MI5, or the Security Service, is primarily responsible for domestic counterintelligence and security within the United Kingdom. Your focus would be on the agency’s missions, including the protection of national security by countering terrorism, espionage, and other threats coming from within the United Kingdom.

While conducting your daily routine, you may not be aware of MI5’s extensive network of officers and agents working behind the scenes to ensure safety within the country. With their specialized skills and dedication to upholding the law, they operate under strict legislation to maintain the highest standards of professionalism.

MI5 Legal Framework

As an MI5 officer, your activities are regulated by various British laws and regulations. The primary legal framework that governs MI5’s activities is the Security Service Act of 1989. This Act establishes the legal basis of MI5, its functions, and its authorities about national security, counter-terrorism, and counter-intelligence operations. Moreover, the Investigatory Powers Act of 2016 sets out the conditions under which MI5 can carry out surveillance or other investigatory activities.

To protect your individual rights and those of the public, MI5 is also subject to oversight from the Investigatory Powers Commissioner’s Office (IPCO). The IPCO ensures compliance with the laws governing MI5’s work. It is important to be aware of and adhere to these legal guidelines to safeguard the integrity of your work and the reputation of the organization.

MI5 Milestones

Established in 1909 as the Secret Service Bureau, MI5 was founded by Captain (later Major General) Vernon Kell. During World War I, MI5 played a central role in the capture of most of Imperial Germany’s intelligence agents in the UK. In the years following the war, MI5 was restructured, and MI6 was created.

MI5’s antecedent can be traced back to Sir Francis Walsingham, Queen Elizabeth I’s spymaster from 1573 to 1590. He recruited informers, cryptographers, and seal-breakers to form a protective spy ring around the Queen. This served as a foundation for the future development of MI5 as a modern intelligence agency.

MI5 in Popular Culture

The UK’s internal intelligence agency is MI5, or the Security Service. They are responsible for protecting the country against threats to national security. In popular culture, MI5 has been portrayed in various ways, which might influence the public perception of the agency. For instance, television series like Spooks present a dramatic and suspenseful view of MI5 operations, showcasing its agents’ dangers and challenges while defending the country from various threats.

MI6 in Popular Culture

MI6, formally known as the Secret Intelligence Service (SIS), is the UK’s external intelligence agency. They focus on protecting and promoting British interests and security overseas through various means, including espionage. The most iconic portrayal of MI6 in popular culture is undoubtedly the James Bond series, with its suave and resourceful agent 007.

While the James Bond movies are highly entertaining, they might give a somewhat exaggerated and sensationalized view of MI6 operations. Nevertheless, they have undeniably increased public awareness and interest in international espionage. Other portrayals of MI6 in media, such as Smiley’s People and the John le Carré novels, offer a more grounded and realistic depiction of the agency’s work.


What is MI6? 

MI6(Military Intelligence, Section 6), commonly known as SIS (Secret Intelligence Service), mainly combats external threats.

It is responsible for gathering information about intelligence outside the UK regarding government security, foreign, defence, and economic policies. 

The main aims of MI6 are to counter-terrorism (stop terrorist attacks in the UK), disrupt hostile state activity (tackle threats from hostile states and promote UK’s prosperity), and cyber advantage (promote and defend the UK’s cyber realm and use the UK’s cyber to reduce threats).  

During the 1930s to 40s, it was the most effective intelligence service in the world as it conducted espionage operations in Europe, Asia, and Latin America. 

MI6 is sometimes using the cover name Government Communication Bureau. The members of MI6 secretly work around the world to make UK safe from external threats.

MI6 works with GCHQ, MI5, law enforcement, HM Armed Forces, and other international agencies.  

Sir Mansfield George Smith-Cumming was the first director of the Secret Intelligence Service (SIS).

At the time of war, when there was a need to acquire more information about Germany’s new navy, the head of MI6 (SIS) Cumming was known as “C”, which evolved into a code name because he used to sign correspondence with his initial C in green ink.

In contemporary, the head of MI6(SIS) is still called “C”. 

MI6 Structure

MI6, also known as the Secret Intelligence Service (SIS), is responsible for gathering foreign intelligence to support the UK’s national security interests. It is tasked mainly with covert overseas collection and analysis of human intelligence. The head of MI6 is called the Chief, who reports directly to the Foreign Secretary.

Like MI5, MI6 is also organized into different divisions, each focusing on a specific aspect of intelligence gathering and analysis. Some key components within MI6 include:

  • Operations Directorate: Responsible for conducting intelligence operations across the globe.
  • Analysis Directorate: Tasked with analyzing and evaluating intelligence collected by operational officers.
  • Technical Directorate: Provides technical support, including advanced equipment, surveillance, and communications technology.

MI6 works closely with other UK intelligence agencies, alongside international partners, to effectively achieve its mission of protecting the nation’s interests and security.

MI6 Operations

As someone interested in international affairs, you may focus on MI6 or the Secret Intelligence Service (SIS), which handles the United Kingdom’s external intelligence-gathering efforts. It is responsible for promoting and protecting British interests and security overseas.

If you examined this agency more closely, you would find that MI6 conducts operations in foreign countries, gathering strategic and valuable intelligence critical to the nation’s decision-making process. Agents in this service work tirelessly to collect information that may affect global security, diplomatic relations, or Britain’s economic interests.

MI6 Legal Framework

As an MI6 officer, your professional responsibilities are directed by different legal frameworks from those that govern MI5. The most pertinent legislation that sets the foundation for MI6 activities is the Intelligence Services Act of 1994. This Act allows MI6 to carry out its mandate of protecting and promoting British interests and security overseas.

The Investigatory Powers Act of 2016 also applies to MI6 operations. This Act puts forth the legal groundwork for various investigatory actions, such as surveillance and interception, necessary for protecting national security. Compliance with these regulations is crucial for upholding the organization’s legitimacy and trustworthiness.

MI6 Milestones

MI6’s roots can be found in the British naval intelligence department, which played a significant role during the First World War. Focused on the German threat, MI6 was tasked with infiltrating enemy countries. Unfortunately, it was largely unsuccessful in infiltrating Germany during the war.

In World War II, MI6 shifted its focus to covert operations and supporting European resistance movements. Its effort to gather intelligence and resist enemy forces played a crucial role in the Allied victory.

The Cambridge Spy Ring was an infamous counterintelligence effort by MI6. It involved infiltrating international intelligence services and exposing several double agents, highlighting some vulnerabilities in British intelligence during the 20th century.

MI6 in Popular Culture

MI6, formally known as the Secret Intelligence Service (SIS), is the UK’s external intelligence agency. They focus on protecting and promoting British interests and security overseas through various means, including espionage. The most iconic portrayal of MI6 in popular culture is undoubtedly the James Bond series, with its suave and resourceful agent 007.

While the James Bond movies are highly entertaining, they might give a somewhat exaggerated and sensationalized view of MI6 operations. Nevertheless, they have undeniably increased public awareness and interest in international espionage. Other portrayals of MI6 in media, such as Smiley’s People and the John le Carré novels, offer a more grounded and realistic depiction of the agency’s work.

Prominent MI6 Staff

While MI6 remains a highly secretive organization, several prominent figures have risen to public prominence, including the following:

  • Sir Mansfield Cumming: As the first chief of MI6, Cumming held the role from 1909 to 1923. He is known for creating the tradition of referring to the head of MI6 as “C” and signing documents with a green ink pen.
  • Major John Sinclair: A key figure in the organization, Sinclair served as chief of the Secret Intelligence Service (SIS) during World War II and oversaw the expansion and modernization of the service.
  • Sir Richard Dearlove: Appointed in 1999, Dearlove served as chief of MI6 until 2004 and played a central role in the intelligence community’s response to the September 11 attacks.

Main Differences Between MI5 and MI6 

  1. The main objective of MI5 and MI6 is that the latter work overseas to help the UK to make it safer and prosperous, whereas MI5 helps to keep the country safe. 
  2. Regarding accountability, MI5 is responsible to the home secretary, Priti Patel of the Home Department. On the other hand, MI6 is accountable to Dominic Raab, who is the Foreign Secretary. 
  3. MI6 mainly includes several secret political exploit triumphs, while MI5 concerns domestic or internal security. 
  4. At the time of the First World War, Kell, or “K”, the head of MI5, and Cumming, or “C”, divided their work. “K” was responsible for counter-espionage within the UK, whereas “C” was responsible for gathering intelligence overseas.   
  5. MI5 is formally known as the Secret Service and deals with internal matters. In contrast, MI6 is known as the Secret Intelligence Service and deals with external matters. 

Comparative Analysis

When examining the differences between MI5 and MI6, it’s essential to understand their unique roles and responsibilities. MI5, officially known as the Security Service, primarily focuses on domestic security within the United Kingdom. Their mission is to protect the country and its citizens from threats like terrorism, espionage, and cybercrime.

On the other hand, MI6, formally known as the Secret Intelligence Service (SIS), operates outside of the UK and is responsible for gathering foreign intelligence. Their main objective is safeguarding national security and promoting British interests overseas through espionage and other covert activities.

In terms of structure, both MI5 and MI6 operate under the jurisdiction of the Home Office and the Foreign and Commonwealth Office, respectively. This division of responsibility helps ensure a clear separation between national and international matters.

As for their scope of work, MI5 mainly deals with information security, counter-terrorism, and counter-espionage within the UK. Their primary goal is to prevent any potential threat to the nation’s security. This includes monitoring individuals and groups that may pose a risk to the UK and its citizens.

Conversely, MI6 focuses on foreign intelligence gathering, meaning their operatives work mostly outside of the UK. They collect and assess information that can help inform the government’s decision-making process regarding different aspects of foreign policy, such as diplomacy, military action, and international trade.

Lastly, the methods used by these two organizations differ significantly due to their varying objectives. MI5 focuses on intelligence gathering through surveillance, monitoring, and covert operations within the UK. In contrast, MI6 employs a more diverse techniques, including recruiting agents, intercepting communications, and conducting covert operations in foreign countries.

Difference Between MI5 and MI6
  1. https://www.tandfonline.com/doi/full/10.1080/08850600701249758
  2. https://books.google.com/books?hl=en&lr=&id=IFLpJ1byJisC&oi=fnd&pg=PT5&dq=MI6&ots=jXn0Z9ge3R&sig=q6Wm5SQ_7-n4rKX5n5MQ37wayjk

Last Updated : 14 October, 2023

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