Bernard Newman is a part-time agent with British Intelligence.
If you have some confusion over the fact that the name of this protagonist is the same as the author of these adventures, allay your concerns for they are indeed one and the same. These many "missions" that the man undertakes on behalf of the United Kingdom are said to be semi-biographical fictionalized remembrances.
Newman is an interesting man, to say the least. He talks repeatedly of his "modest successes" in helping British Intelligence with this small but vital matter here and that insignificant but vital matter there; in all matters his part is downplayed repeatedly in the accounts but in a way to ensure no one forgets he was the linchpin to all the successes.
Newman will be given the rank of Captain in the British Army thanks to his many escapades on behalf of their Intelligence division. He sees no real (that I can find) action on any official battlefield but he definitely earns his plaudits in the back alleys and dark corners and dank rooms where covert activities are constantly changing the fortunes of armies.
He comes to the covert work thanks to his "knowledge of Europe and my most un-English command of languages - the latter the heritage of an Alsatian mother". Because the region of Alsace has been fought over by the French and the Germans for a couple hundred years, those living there have a total grasp of both languages and both histories. His father was a Englishman who was on a walking-tour (hiking trip for Yanks) in the Black Forest when he happened to meet his future wife who was there visiting a school friend. After the two married and Newman came along, the young man would spend much of his time in England with his parents and in Alsace during the summer months.
Newman inherited his father's love of taking those protracted walking trips as well as a devotion to bicycle riding tours all over Europe in the years before the hostilities of WWI began. [While little mention is made of his source of income, it is implied that money was never an issue Newman had to worry about.] As a result of his many, many forays all over the Continent, from the northern parts of Holland, Denmark, and Germany to the southern climes of Spain and Portugal and Italy and the Balkans, Newman learned all the various parts and gathered good friends in all these regions. These friends would come in handy over the years.
In the many adventures that exist in which Newman takes part, he is usually working closely with someone who Newman gets temporarily connected.
In the beginnings it will be a Sergeant Marshall, later Inspector, with what is initially called "Special Service from Scotland Yard" and later the Special Branch. In a considerable number of adventures Marshall will play a major role though it is the first few that Newman describes in which Marshall is most prominent; his later parts are always vital but often less visible. From the beginning of their relationship, however, the friendship between the two is strong; Marshall was the best man at Newman's marriage to his beloved Margaret.
After a short time, the friendship, and unofficial partnership, of greatest significance to Newman's chronicles will start with the ever-interesting "Papa" Pontivy. This highly regarded and quite remarkable French detective has at times worked for both the Deuxieme Bureau (external security) and the Surete Nationale (internal security) and is the man to call whenever there is a turf war between the two.
In addition to handling major matters of espionage and state security, Newman has had time for helping solve the occasional "mundane" murder or two. These are brought to his attention likely as a result of his occasional profession as a traveling reporter/correspondent., though how much time he actually spent being such is debatable (hence my earlier comment about his income or lack of need for such).
One thing for certain about this version of Captain Bernard Newman is that the man loves, indeed seems to live for, excitement and saving the day. And he is pretty good at it, if he does say so himself.