To report an imminent threat call 999 or ring the Anti-Terrorist Hotline on 0800 789 321
Current national threat level: SUBSTANTIAL Read more about threat levels >>

CASES FROM THE NATIONAL ARCHIVES

The National Archives holds more than 5,000 declassified Security Service files dating from the Service's earliest days through to the late 1950s. More are being released each year.

These pages provide some examples of MI5 documents from The National Archives, illustrating the careers of three key 20th century spies.

Fact or Fiction?
MI1-MI4 still exist in secret.

True False

Latest News

view ALL News

Seeing MI5 differently

International Day for Persons with a Disability gives MI5 the opportunity to confirm our commitment to working together...

Read Full Article ›

MI5 remembers: Armistice Day 2019

MI5 marks Armistice Day 2019 with Remembrance service and wreath laying

Read Full Article ›