Like any major organization, a spy service must constantly endeavor to improve. But unlike most other industries, learning from competitors is not that easy in the spy business. After all, organizational methodology and operational tactics are some of an intelligence service’s most closely guarded secrets.

But there are two human-intelligence focused spy agencies can learn from each other: the CIA and its British equivalent agency, the Secret Intelligence Service. With many shared interests, these two services work together to define the special relationship between the two countries. Only the NSA and its British equivalent, GCHQ work more closely together. Thanks to that trust, the two services have the ability to scrutinize each other for their own improvement.