MI6s

MI6s is not an official designation. The organization most commonly associated with the term is the Secret Intelligence Service (SIS), the United Kingdom’s foreign intelligence service, which is widely known by its historic nickname, MI6. In official use, the agency is referred to as SIS or by the nickname MI6 in public discourse; the plural form MI6s is generally considered informal or incorrect in formal contexts.

The SIS has its roots in the Secret Service Bureau, established in 1909 to collect foreign intelligence. In 1916 the bureau was split, giving rise to MI5 for domestic security and MI6 for overseas intelligence. After World War II the service adopted the formal name Secret Intelligence Service, while the MI6 label continued as a commonly used alias. The agency operates under the Foreign, Commonwealth and Development Office and is overseen by the Intelligence and Security Committee of Parliament.

Its primary mission is to obtain foreign intelligence that informs government policy and national security. Core activities include human intelligence gathering (HUMINT), covert overseas operations, analysis to support policy decisions, counter-terrorism, weapons proliferation monitoring, and collaboration with allied intelligence services. The SIS employs officers and staff in London and abroad, supported by technical, analytical, and logistical units.

Publicly available information about the SIS emphasizes legal frameworks, parliamentary oversight, and annual reporting, while much of its work remains confidential. The term MI6s, when encountered, typically refers informally to MI6 personnel or, less accurately, to the organization as a whole. The agency is widely portrayed in popular culture, though such depictions often differ from its actual procedures and constraints.