The East German River Crossing...
For those of you who have wondered where Smiley waited for Karla to make his crossing into the Western Sector, I have the film location for you - in England. If you go to the Flickr site and key into the finder, "John le Carre & Sir Alec Guinness" you will be presented with a choice of photographs. Amongst these you will find a newspaper photograph of them both, as well.
What are you waiting for?