Blackadder was one of our favorites, but in the "collections" it's really 4 or 5 separate series. The "humor" varies with the era depicted - or it seemed so to us.

Are You Being Served was another that had a long run and lots of reruns in the US, and wasn't "out of reach" for non-Brits, while still having a lot of great (subtle?) humor.

Butterflies was one of very few programs that Lin actually made a point to try to watch occasionally, so I guess it might be said to have a good "crossover" appeal while still conveying some "Brit attitude."

Benny Hill was funny, mostly, but impressed us more as "juvenile" humor than as peculiarly British; but I suppose based on the few hundred "greenies" I've worked with, possibly "puerile" is an important element in some "British humor." (They mostly claimed to be "ruggers" as well.)

John