After Calderero, sastre, soldado, espía (1979), Producer Jonathan Powell was going to film a sequel, an adaptation of John le Carré's sequel novel "The Honourable Schoolboy". However, that novel was set in Hong Kong, and so it was thought to be too expensive to film. Powell skipped to the subsequent novel, "Smiley's People".
Simon Langton was brought in to direct this mini-series after Sir Alec Guinness demanded a change of directors because the initially assigned director had a reputation for bullying actors and actresses.
Simone Signoret was initially approached for the role of Madame Ostrakova, but her fee was too high. Judi Dench was the next choice but she was unavailable due to an operation on her foot. Rita Tushingham and Brenda Bruce were also considered before Eileen Atkins was finally cast.
John le Carré partially based his famous George Smiley character on a friend, the Lincoln College tutor and Oxford University don, the Reverend Vivian Green. Smiley was also based on le Carré's boss at MI5,
Lord Clanmorris (1908-1988), who wrote crime novels under his given name, John Bingham.