As a former practitioner of the dark arts described in this film, I attest to the verisimilitude of a lot of the matter of the film.
In particular, the seedy, shoddy government premises that were characteristic of such establishments before the GWOT scattered money far and wide seem very familiar and "real." Anyone who remembers the dilapidated temporary buildings that housed much of the CIA on the Mall along Constitution Avenue or the god awful collection of similar buildings that sheltered DIA at Arlington Hall Station must agree.
The film is set in 1973 at the height of the Cold War. The underlying plot feature is a search for a "mole" put in place at the top of the "Circus" (MI-6). This is clearly based on the Kim Philby story as well as that of a lot of other dastards in the British services of that time. The mole is uncovered at the end and dealt with appropriately. He tells George Smiley, a wonderful and endearing character, that he "had to make a choice because the West is just so rotten." That motivation seems to have been true of many of the Cambridge University "Apostles" who were recruited by Arnold Deutsch. Deutsch was possibly the greatest espionage recruiter of all time in any service, in his case the NKVD. When Deutsch recruited them, they stayed recruited for life. He was, of course, killed in the Blood Purges of he late '30s. Stalin did not believe such recruitments were possible.
For me the best parts of the film are faithful reproduction of the internal bueaucratic struggle among the mandarins of the Circus. I still have the scars.
As a piece of cinematic art, the film is, IMO, very nearly flawless. It is very much a European film. Americans, in general, are too intellectually sterile to create such a film or to follow the dialogue. The director is Swedish. The only other film of his that I have seen was "Let the right one in." This is a bizarre story about child vampires trapped in child bodies in the Swedish night. It was creepy.
No, the very best part of the film is the manic Christmas party that is shown in snatches throughout. At one point a Santa Claus appears wearing a mask with Joe Stalin's face. He leads the standing assembled British spooks in singing the Soviet national anthem. It gave me chills and brought back a Christmas party to which I was invited just after the fall of the USSR. At this party the assembled US spooks, all of them Russian specialists, sang "We're dreaming of a Red Christmas, just like the ones we used to know." They were finished. They knew it.
Many have now been reborn as CT analysts. Isn't that right, Basilisk?
It's a great flick, if you are up to it. pl