- Creator Backlash: In the prefaces to the republished novels, John le Carré argues that Smiley had outlived his potential as a character by the end of Tinker Tailor Soldier Spy, in large part because of real-life changes in the political climate.
- What Could Have Been:
- John le Carré had originally planned several novels involving Smiley and Karla, one of which would have been set in the Middle East. This one was scrapped when le Carre couldn't figure out how to fit Smiley in that setting; part of the story and research le Carre had planned here would later end up in his novel The Little Drummer Girl.
- Judi Dench was supposed to play Madame Ostrakova in the TV version, but wasn't available.
Trivia / The Quest for Karla