Fine adaptation of le Carré's first novel, with Mason as ersatz Smiley, Charlie Dobbs (le Carré had sold the rights to the name with the rights to The Spy Who Came In From the Cold). Andersson is badly miscast, and the subplot with her character is a rather unnecessary addition to the script, but the rest of the reliable cast is fine, and the climax at an apt performance of Marlowe's nasty Edward II is quite good.
Freddie Young's cinematography, his first experiment with the muted colour palette that would prove to be so influential, along with Quincy Jones' soundtrack, set the perfect tone for Paul Dehn's somberly witty script. Overshadowed by its more well-known predecessor, the aforementioned The Spy Who Came In From the Cold, but highly recommended.
Note: Andersson is obviously dubbed; unsure who, possibly Nikki van der Zyl?
Thanks to Philly for all his help once again!!