MI5 (Military Intelligence, Section 5), [2] officially the Security Service, is the United Kingdom's domestic counter-intelligence and security agency and is part of its intelligence machinery alongside the Secret Intelligence Service (MI6), Government Communications Headquarters (GCHQ), and Defence Intelligence (DI).

Thames House is an office building in Millbank, London, on the north bank of the River Thames adjacent to Lambeth Bridge. Originally used as offices by Imperial Chemical Industries (ICI), it has served as the headquarters of the United Kingdom's internal Security Service (commonly known as MI5) since December 1994.

Discover how MI5 works to protect against threats to national security through intelligence gathering techniques, partnerships and legislation. Find out how you can play your part in keeping the...

Palace Barracks, Holywood is a military installation and the Northern Ireland headquarters of MI5, in Holywood, County Down, Northern Ireland.

Find out more about MI5’s mission and core values; our people who work to keep the country safe; and our rich and varied history. Our headquarters, Thames House, in central London is a Grade II...

Our headquarters, Thames House, in central London is a Grade II listed building in Westminster, not far from the Houses of Parliament. Thames House was designed by Sir Frank Baines, the Principal...

MI5 is based at Thames House on Millbank, not far from the Houses of Parliament. The agency is based on the opposite side of the River Thames from MI6. MI6 is located in a more distinctive and modern building, itself previously featured in the James Bond film, Skyfall. Who runs MI5?

The Security Service, MI5, is responsible for protecting the UK against threats to national security. MI5 works with the Home Office is supported by 1 public body.

Regent's Park Headquarters, known internally simply as The Park, is the main headquarters of MI5. The Security Service has used the building as its main base of operations since the late 1990s or early 2000s when the previous headquarters was purchased from the government and turned into the...

Explore the ever-changing world of espionage and security threats through original case files, photographs and papers, alongside the real equipment used by spies and spy-catchers over MI5’s...