Smiley's People

Patrick Stewart had a non-speaking role in the BBC mini-series Smiley's People (the trivia question from the last post). Based on John le Carre's novel. It was an interesting mini-series, but I'm sure it would have made more sense if I had either seen or read the prequel Tinker, Tailor, Soldier, Spy. Patrick Stewart is also listed only in the final episode of that mini-series, so I'm guessing another non-speaking role. If anyone knows for sure I'd appreciate any info.