Just watched the entire 1979 miniseries "Tinker Tailor Soldier Spy" and enjoyed it immensely!
In case you don't know about it, it's based on the 1974 espionage novel by John LeCarre' and it stars Sir Alec Guinness as retired British intelligence officer George Smiley who is called back to find a Soviet mole planted in a top position at MI6.
There will be a movie remake this October starring Gary Oldman, so I decided to see the original first.
I can recommend this, but don't be expecting a James Bond or Jason Bourne type of spy thriller: No car chases and only the smallest amount of gunfire. This focuses on the mental and, more to the point, emotional side of espionage...especially the toll it takes on the people involved.
My next step is to go out and find a copy of the original novel.