Oliver Keene is an agent with the British Secret Service.
Keene, at the time we first meet him, is a veteran of many years of duty with the British Intelligence, some spent in the early years in the Mediterranean as evidenced by the fact that one of his many languages was Greek. However, by his words to a fellow agent in the first recorded adventure, we learn that he has spent most of the past years, by inference I calculate at least 10, in "Asia" and by further analysis certainly in South-East Asia. I further place the region as most likely India or Burma since he talked of changing his area of operations due to "not much happening" in that section and considering the expansion by Japan in Northern and Central Asia around the time of the adventures, it is unlikely he would use that phrase if he had been stationed anywhere around China.
Keene goes by, at times, the nickname of "O.K." based on his initials. These leads on more than one occasion to brows furrowing in confusion when he states, "I'm O.K.". He does this on purpose, though, because his face is ready to break into a grin after he sees the doubt.
He possesses, according to one young woman, a "tantalizing grin" which he flashed often, usually before breaking into a solid laugh. Keene, despite the many troubles he finds himself in, loves to laugh and he can see the humor in far more things than most people can considering the times he chortles is often after being shot at. It is obvious he enjoys the danger of his profession and savors the times when he has not had to pay dearly for that danger.
More on this interesting agent as I finish more adventures.
For now, there are a couple of interesting passages which describe or comment on Keene:
"He had an irritating habit of dropping into cliches that would have annoyed [any man]."
After slouching back in his chair with "his eyes practically closed", it was stated that "It was a fad of his to assert that one could hear better free from all visual distractions. Others who had tried to emulate him usually found themselves falling asleep."