I’d recommend becoming familiar with his wealth of works, particularly the Smiley novels and his later ones, not long before he died. Also, the TV adaptations of T,T,S,S and Smiley’s People, plus The Spy Who Came in from the Cold 60s movie. Saying that, my other half hasn’t read any, but like many has seen the films and modern TV adaptations. She really enjoyed The Pigeon Tunnel. I don’t really want to review it more than that. People can discover for themselves. It was more a recommendation.