John Savage is an agent for British Intelligence.
The actual agency for which John Savage works in the Intelligence community is never named - he just answers to a man named Gordon Circle who apparently holds considerable power without the trappings. As cover for this department, Circle ran, along with his brothers Howard and James, the Circle Sporting Goods company, a real establishment that turned a good profit. None of the three men were really related and none really had the last name Circle but the cover was a good one and remained intact.
For this agency, Savage is their number-one go-to guy, the man most certain to get the job done. His particular cover to camouflage his movements and sometimes his need for lethal tools was as the owner and chief guide for Savage Safaris. With this profession, Savage is able to either take a small group in as the cover or use scouting for future tours as the reason for the visit.
As the go-to guy for Circle, Savage is considered an uncouth, albeit superbly trained killing machine, a man who will kill whoever needs it if the price is right. Even more disturbing to some who have to deal with him, John Savage seems to enjoy the mayhem. He definitely takes considerable satisfaction on a killing done well.
Tact is not a word to be used with Savage. At a formal dinner party with the new President of a South American country, a woman started to rub her hand uninvited on his leg and he none-too-quietly or unobtrusively placed a butter knife on the back of her hand and offered to cut it off if she did not stop. It amused at least one guest, made enemies of a couple, and showed that Savage had no use for niceties or diplomacy.
In the cover of both paperbacks Savage is shown to wear an eye patch over his left eye. I found no reference to such a liability in the books but it is likely there somewhere.