I once heard someone say morality was method. Do you hold with that? I suppose you wouldn't. You would say that morality was vested in the aim, I expect. Difficult to know what one's aims are, that's the trouble, specially if you're British.
I'm fairly sure I read this as a teenager, but on rereading in advance of new movie version I remembered nothing: so perhaps it was a first read after all.
This is not James Bond territory: this is careful, slow, painstaking brain-work done in smoky rooms and rainy doorways by unglamorous individuals, mostly male. Tinker Tailor Soldier Spy has considerably more depth than the plethora of spy stories inspired by Fleming's Bond: it is, at heart, a story about love and betrayal, on the personal as well as (or, perhaps, at the root of?) the patriotic level.
George Smiley, forcibly retired from a career in espionage after the death of Control, is trying to discover the identity of the mole who's betrayed various British agents to the Russians. Jim Prideaux, the invalided former spy whose career as a teacher at a minor public school frames the narrative, is also keen, for rather more personal reasons, to find whoever set him up on his last mission. There are a number of possible traitors, and an equal if not greater number of loose cannons. And beneath it all lies the grinding conflict of the Cold War, and the receding memory of World War II preceding it.
Tinker Tailor Soldier Spy is very much of its time: the older characters (Smiley, Jim Prideaux, Bill Haydon, Oliver Lacon) grew up in the 1930s when espionage had a kind of glamour; then they fought in that war and saw their friends die. For the younger characters (Ricki Tarr, Peter Guillam, Percy Alleline) the war is mere history, and the intelligence game has always been slightly sordid.
The character who fascinates me most is probably Jim Prideaux, with his background of minor European nobility, his peripatetic lifestyle, his sheer endurance and his capacity for emotion. I'd read whole novels about him.