It’s the rough equivalent to the US Central Intelligence Agency, but it rarely gets public attention. Strategy Page has a thumbnail sketch of the organization as it gets a brief mention in the British press for its operations against Libya:
MI6 is less than one tenth the size of the CIA (in manpower) and has a budget that’s even smaller. But the CIA is by no means ten times as effective as MI6. For all its size and resources, the CIA cannot, or often will not, do things that MI6 will. Part of this has to do with MI6s greater experience and need to make do with less. But a lot of it has to do with different styles of operation. Both organizations are in the overseas espionage business, but both go about their business in quite different ways, and with often quite different results.
A large part of the difference can be traced to the fact that MI6 has always had a healthier relationship with its diplomats. CIA agents operating overseas often operate out of the local US embassy. Their cover is a diplomatic passport indicating they work for the State Department. But from the beginning, the diplomats were hostile to this sort of thing (British diplomats were not.) So CIA people were forced to use diplomatic passports indicating they were part of the Foreign Service Reserve instead of just Foreign Service. For those in the know, and that means just about everyone, it was easy to find out who the CIA guys were.
MI6 has a degree of legal cover for its operations that the CIA could only envy. Under the Intelligence Services Act of 1994, MI6 officers have immunity from prosecution for crimes committed outside Great Britain. The Criminal Justice Bill of 1998 makes it illegal for any organization in Great Britain to conspire to commit offenses abroad, but Crown agents have immunity. Which means, in effect, that yes, Her Majesty’s Secret Intelligence Service really is licensed to kill.
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Another advantage of MI6 is that they have a number of SAS commandos trained to work with MI6 and are always available for any MI6 needs. This commando organization is called Increment and is used for assassinations, sabotage or other dangerous jobs (like arresting war criminals in the Balkans.) In addition, every station chief has a direct line to SAS headquarters and a good working relationship with the commandos.
