Another constantly, and meticulously, maintained British Secret Service front, this time an extermination service for vermin, insects and similar problematic creatures, in the Home Counties primarily.
One of several useful "fifth columns" MI6 can slip in almost anywhere, although agents loathe being sent out on the banal jobs that provide the requisite cover and job experience. Most assume, when first assigned, that it is some kind of initiation test, and would have been happier had it proved so. It is frequently referred to in-house as "X-Off" ... and worse. Attempts to be "X-Men" and similar have died torturous deaths, and endured endless momentary, reviled resurrections.