One autumn night in 1991, I stood on the rooftop terrace of a tacky villa in Saranda once owned by Albania’s Stalinist dictator Enver Hoxha, beside three elderly former SOE officers who were returning to Albania for the first time since 1945. In an image that summed up the waste and the horror of the Cold War, David Smiley stared out over the dark water at the lights of Corfu, from where, on a similar night in October 1949, he had sent a group of dissidents, code-named the ‘Pixies’, to launch an insurgency — and wiped his eye in silence.

Smiley’s...