"Brains" Cunningham is an agent for Department S-3, British Intelligence.
This highly influential clandestine service has a mandate that seems incredibly broad as Brains gets involved in cases of all sorts, from simple murder to smuggling to secrets stealing to madmen intent on taking over the world. At no time does Brains seem the least surprised or put out no matter where he is sent or what he is asked to do.
Starting near the end of World War II and continuing on well into the 60's, the adventures of Cunningham represent the epitome of cool, suave, in-control behavior that is now often the stereotypical British agent. If ever there could be considered a prototype for this image, Brains is the man, complete with the drawing room and the pipe and slippers.
And as he travels the globe fighting the enemies of the Crown, Brains is constantly accompanied by Pring, his loyal, often lugubrious, batman. While at all times his servant, Pring is also Brains' friend and his assistant. Pring is a very good cook. He is also very good at knives and at sneaking and at street fighting and many other things. Maybe not as good as Brains but still very deadly.
Brains' escapades are often told from the viewpoint of a friend visiting his digs and seeing yet another tricket or oddity in a display case that Brains prominently displays in his drawing room. This case contains some very strange items, not least of which is a shrunken head. Each item has a story behind it and Brains enjoys telling it.