Silas Manners is an agent for British Intelligence.
The exact department for which he works is never specified. In the first of the two-book series, Manners is working as part of a multinational task force dubbed N.A.D.A. (an acronym not spelled out) which was a pooling of intelligence resources from the U.S., U.K., Canada, and others. His role in that force is more of a free agent really answerable only to the President and Prime Minister though he does cooperate and work closely with an American agent. In the second book, he is back home working for his own people. Whatever the department, its newly appointed interim leader is a man who has considerable distaste for men of Manners' ilk and would love to see such people long gone from the community.
Manners appears to be a throwback, in many people's minds, a man who will not hesitate to do whatever is necessary to get the job done. He can engage in playful banter if it is called for but he can just as quickly grab a man by the collar, throw him against the wall, and convince him cooperation is in order. He has killed a larger than average number of enemy operatives in his tenure; though he does not enjoy it nor desire it, he does not hesitate when it seems his life or the other guy's. He chooses his life without a pause.
The age of the agent is never mentioned but the references to the many years of service clearly makes Manners in his mid to late 30's. He is unmarried and has no serious attachment, knowing that his schedule would never allow it and feeling no apparent loss for not having one. He appreciates a beautiful woman but those he meets in his line of work are more apt to be out to kill him than woo him. He allows the latter but the former.
A hard man when needed, Manners notes in one event that he had to be "above mortal emotions" to get his job done. He is hardly an automaton as he can laugh at a good joke, drink sociably, mingle politely, and otherwise exist in any urbane situation. He can also, with a moment's hesitation, strike out with his expert martial arts skills and render an opponent unconscious or worse.