The Spanish Prisoner and The Winslow Boy
I love The Spanish Prisoner, and was eager to see the screenplay, to know if the film changed much in shooting. It didn't: the Rolls dealer originally sold shotguns, a few lines changed. Hardly anything. The central problem (how do they work the switch) isn't clarified in the screenplay, alas. No news here (and it's a tough screenplay to read, since it's filled with descriptions of shots with no dialog) but it's a wonderful story.