From his dialogue with Daisy Banks at The Browser about books on being a spy:
Let’s finish with John le Carré’s classic spy novel, Tinker, Tailor, Soldier, Spy.Read about the other books Baer tagged.
This is beautifully written. But more than that, it is really about counter intelligence taking pieces of information which send you off on a hunt. It is no different than the hunt for Bin Laden, where they took isolated fragments of information and tracked him down. And this is what you see in Smiley. He takes bits of information to find the mole. Anyone who has been on a mole hunt, or watched one from the outside, will say this is the way it goes. And le Carré has the ability to add drama and colour. The Cambridge Five were such a fascinating group. The handler went back to Russia and was executed, but that is another story. For classic espionage in a little town in Germany, you can’t do better than le Carré.
Tinker, Tailor, Soldier, Spy is on John Mullan's list of ten of the best pairs of glasses in literature and among Stella Rimington's six favorite secret agent novels; Peter Millar includes it among John le Carré's best books.