I saw most of
Cambridge Spies years ago, but for various reasons never caught the last episode. Thanks to internet piracy, I now have the whole series.
From what I remember of it, I am kind of surprised that it doesn’t have an enormous fandom, and I was hoping that this wasn’t because it wasn’t as good as I remembered it being. The first episode confirmed that hope—it’s just as good as I remember it being.
Brief summary for those who haven’t heard anything about it: In the 1930s, four (probably five) upper-class British Cambridge students were recruited by the Soviet Union to spy on the UK, and would have gotten away with it were it not for those meddling kids. What am I saying? They got away with it until the 50s and then defected to the Soviet Union. Yes,
this is a real thing that happened. No,
John LeCarré is not exaggerating in his books, or at least, not very much. They included Kim Philby, a high-ranking member of British intelligence, Guy Burgess, secretary to the British Foreign Minister of State, Anthony Blunt, art historian, professor, and knight until they found out about the spying thing, and Donald Maclean, the guy who wrote that “American Pie” song. Sorry, no, not that one. This one was a member of M16.
Also, they were all smoking hot, at least if the miniseries is to be believed.

Anyway,
( Episode 1, with one NSFW screencap )