Le Carré has written more than 20 books and this is the ninth loosely described as a George Smiley novel. The master spy with the guilty conscience and a will of iron is only the main character in four or five of them (depending on whether you think the main character of The Honourable Schoolboy is, uh, the honourable schoolboy.
The narrator and protagonist of A Legacy of Spies, is Peter Guillam, Smiley's protegé, dragged out of retirement to explain some old cases to a post-Cold War generation of interrogators. And that reminds me. I got my filthy hands on a pre-publication copy and I am halfway through it, but I am still trying to figure out when it is set. INternal evidence says it has to be later than 2000. In our present day Peter would be mid-eighties and Smiley, if he is still alive (that is under debate in the part I am reading) would be a decade older. Those would be mighty old spies.
In any case it is a great read.