“How many letters did your Grace write that day?”

“Twenty or thirty. I have a large correspondence. But surely this is somewhat irrelevant?”

“Not entirely,” said Holmes.

“For my own part,” the Duke continued, “I have advised the police to turn their attention to the south of France. I have already said that I do not believe that the Duchess would encourage so monstrous an action, but the lad had the most wrongheaded opinions, and it is possible that he may have fled to her, aided and abetted by this German. I think, Dr. Huxtable, that we will now return to the Hall.”