Dennis Spooner had a very fertile mind. Among his series creations or script work were "Randall and Hopkirk (Deceased)", the premiere episode of "The Champions", "Doctor Who", and "The Avengers." He also was the mastermind behind one of the most consistently great series from the "classic" era of ITC Productions -- "Department S."
The series premise was relatively simple: three diverse agents -- a former FBI agent from America, a computer expert, and a spy novelist -- comprise the most elite branch of Interpol, dealing in the impossible cases. Named "Department S" (the "S" was never explained in the series, but the speculation is that the "S" was for "Spooner", giving both the series and its creator the same initials: D.S.), they had apparent carte blanche (one criminal asked Stewart if he came instead of the police because the police knew they had nothing on the crook) and obtained immediate, sometimes fearful, cooperation (as evidenced by the look on the face of the airport security guard when Jason presents his Department S identification).
The series provided the best combination of what made all ITC shows special. There was suspense (each episode began with an outlandish event, which would result in the Department being contacted), drama, romance (there was obviously "something" between Stewart and Annabelle, although it was never directly expressed or shown -- another reason why the show is so great), and a fair share of humor (usually displayed in the person of Jason King). The character interaction was exceptional, too: instead of having an obvious antagonist among the group, any one of the three could get on the others' nerves at any given moment. Most enjoyable, however, was the tension between Jason and Annabelle. (Some who have written on the series have stated this was not so much "acting", because Peter Wyngarde and Rosemary Nicols didn't get along on the set. If that is true or not, I don't honestly know. It has been reported, and Wyngarde has confirmed, that his nickname for Nicols was "Knickers".)
Jason King was a joy. Although Peter Wyngarde is much better at bad guys (note, for instance, his whip-snapping performance as the leader of the Hellfire Club in the classic "A Touch of Brimstone" episode of "The Avengers", his diabolical laugh as Number Two in "Checkmate" from "The Prisoner", or his gold-stealing surgeon who created "The Invisible Man" in that episode of "The Champions"), he played Jason King with reckless abandonment. Jason was forever badmouthing Annabelle's "undersexed" computer, Auntie.
Annabelle, in turn, had no appreciation for Jason's wild theories about a crime's plot (which he usually concocted by looking at the problem facing the Department and imagining how his fictional character, Mark Caine, would go about solving it). Somewhere in the middle, trying to negotiate peace between his co-workers while working on the case, was Stewart. Sometimes he found "the Charles Dickens of the paperback" as frustrating as Annabelle did; however, Stewart also acknowledged that Jason had "a very nasty habit of scoring near misses" with his unorthodox theorizing.
Aside from the unique plots, "Department S" had another very unique quality for its time (in the late 60s). The official head of the Department was Sir Curtis Seretse. This was one of the first times in a television series that a black man was featured in a role of such prominence and importance. The late Dennis Alaba Peters played Sir Curtis, a man who was usually notifying the Department of its chores between his busy schedule as diplomat. On a couple of occasions he became part of the investigation.
Although not available domestically, "Department S" is on DVD through Umbrella Entertainment in Australia. The seven DVDs feature a number of extras (including commentary from Wyngarde on Sir Anthony Hopkins' performance in "A Small War of Nerves") and are NOT region coded (meaning they will play in any DVD player anywhere in the world).