MI5 - Security Service

MI5 or MI6?

You may be considering a career with MI5 or MI6 and wondering what the difference is between them.           

MI5 headquarters at Thames House.

Terrorism, the proliferation of weapons of mass destruction, espionage and regional instability are some of the major challenges facing us in the 21st century. The Security Service (MI5) is the UK's security intelligence agency. It is responsible for protecting the UK, its citizens and interests, against the major threats to national security.

The Secret Intelligence Service (SIS, or MI6) operates world-wide and is responsible for gathering secret intelligence outside the UK in support of the government's security, defence and foreign and economic policies.

Where the threat has an international angle, MI6 works closely with MI5 in its efforts to counter terrorism, espionage, sabotage and weapons proliferation in the UK. MI6 detects and disrupts terrorist threats to the UK and its interests overseas. MI5 works to disrupt these threats in the UK.

MI6 runs covert operations worldwide using human and technical sources, as well as liaison with a wide range of foreign intelligence and security services. MI5 mounts covert operations within Great Britain and Northern Ireland using similar methods. Both MI5 and MI6 recruit agents – people who are to provide key intelligence on terrorists' plans and organisations.

MI5’s headquarters is at Thames House in London, across the river from MI6’s headquarters at Vauxhall Cross. Andrew Parker is responsible for the work of MI5, for which the Home Secretary has Parliamentary accountability. Alex Younger is responsible for the work of MI6, for which the Foreign Secretary is accountable in Parliament.

MI5’s network of offices is based across Great Britain and in Northern Ireland and you can expect to spend one or two postings at regional stations during the course of your career. These postings will be for two to three years and you can be accompanied by your family.

In contrast, MI6 has people stationed across the globe. Most operational officers undertake at least one foreign posting. These usually last for two to three years, and officers can generally be accompanied by their partners and children.

The third UK intelligence agency is the Government Communications Headquarters (GCHQ) based in Cheltenham. GCHQ counters threats that compromise national security through the production of signals intelligence (known as SIGINT) and the security of communications and information systems (known as Information Assurance). 

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Woman walking through a corridor.

Advice for applicants

Owing to the sensitivity of our work, we do not publicly disclose the identities of our staff. Discretion is vital. You should not discuss your application, other than with your partner or a close family member, providing that they are British. You should also make them aware of the importance of discretion.