It's funny, really.
The "British Invasion" of the 60's not only brought artists like Herman's Hermits, the Rolling Stones, the Who, Petula Clark, Cliff Richard, the Beatles, and the Moody Blues to our shores, just to name a few, but the British also had been importing some of their television shows here as well, something that had been going on since before the start of Beatlemania.
Lord Lew Grade's ITC imported several series during the 50's, 60's, & 70's, mostly spy & adventure shows. Of course, the most famous of those imports included The Saint and The Persuaders, both starring Roger Moore. The train stopped, however, after Space: 1999 and The Muppet Show, the latter produced in America, arrived in the mid-to-late 70's. You'd be surprised to know that, aside from The Saint, the average lifespan of a spy series from ITC was about 1 year. That's it. Danger Man, known here in the US as Secret Agent to most folks, is the only other one I know of that went past a year.
Department S was one of those one year wonders, although it did get 2 seasons. Launched as a mid-season replacement in the Spring of 1969, the series managed only 28 episodes total, which were imported to the US in the mid-70's. I have a recollection of seeing this show on WOR in NY on a Saturday night at one point.
However, Department S was not so much about spies, but rather unusual crimes. A different sort of whodunit, though the team seemed to be England's answer to the IMF (Mission: Impossible). Stewart Sullivan (Joel Fabiani) was the field leader, teamed with author-playboy-adventurer Jason King (Peter Wyngarde) and analyst Annabelle Hurst (Rosemary Nichols). King would later be spun off into his own self-titled solo series, which never made it here to the US.
Here's the episode, "A Cellar Full of Silence". Author Terry Nation might be better known to sci-fi fans for his contributions to Doctor Who.
As noted, the series aired in NYC, but not locally, in a brief syndication run. There were others that met the same fate, as we'll see down the road.