John Meredith is an agent with the Foreign Office.
Agent ... official ... police inspector ... knight.
Each of those terms seem applicable to this man who, according to one source I read (Pretty Sinister Books) says "Our hero is the inscrutable Sir John Meredith, a Foreign Office agent who becomes a policeman almost by accident".
More: "Meredith is not at all a likable man in this book. He comes off as arrogant, classist, and racist. Surprised? I'm not. He has little patience for anyone, insults people to their faces passing it off as wry wit, is constantly telling his colleagues to shut up and is generally one of the worst examples of the uber-macho self-styled aristocrats found in pre-WW2 era fiction written by British men."
After my initial posting, I heard from a fellow spy fan who has this take on Sir John. "Sir John is smarter than most other characters in the stories and doesn't suffer fools easily. The books are very imaginative and full of promise." This reviewer also comments that the author, Francis Gerard, was "heavily influenced by Edgar Wallace and you see his hallmarks throughout." Since I enjoyed the few Wallace books I have read, a lot, I do look forward to giving these books a try myself now.