MI5's early years

Vernon Kell in uniform

The beginnings

Established in 1909 as the Secret Service Bureau, MI5 and MI6 soon grew from modest beginnings to become professional and effective intelligence agencies. 

Our organisation was founded by Captain (later Major General) Vernon Kell and played a central role in the capture of most of Imperial Germany's intelligence agents in the UK at the start of World War I.

Find out more about the establishment of the Secret Service Bureau

Wartime MI5

MI5 directors pictured during World War I
MI5 in World War I

The round-up of the German spy network & wartime expansion.

Black and white image of German spy Carl Lody
Carl Hans Lody 

The story of how MI5 captured a German spy in Britain in 1914.

Between the wars

After World War I MI5's size was reduced drastically as a result of post-war cost-cutting and for a time the Service's very existence came under threat.

World War II

During World War II, MI5 played a key role in combating enemy espionage, intercepting German communications and feeding misinformation back to Germany.

The Cold War

Subversion and Soviet espionage were key concerns during the Cold War, and from the 1970s onwards terrorism also emerged as a serious threat to national security.

A modern MI5

As the Cold War came to an end, major reforms were put in place and the Service gained its first female Director General. The rise of Islamist terrorism at the end of the 1990s led to major changes in the way MI5 operated.

National Archives

You can learn more about the history of MI5 at The National Archives. We periodically release files to The National Archives which cover many aspects of our work.