The United Kingdom is home to two spy agencies—MI5 and MI6. Both were founded in the early 20th century when the British government was increasingly concerned about the threat to its empire posed by Germany’s imperial ambitions. Agents working for these secret services were used throughout both World Wars, and the subsequent Cold War, when the USSR became the country to watch. But while each share a common aim, namely the defense of the realm, they operate in very different ways.
So, what exactly is the difference between MI5 and MI6? Click through this gallery and uncover some surprising facts about Britain's secretive intelligence agencies.