The Sultan Is Vacationing In Greece
If you figure out how and why the Sultan is in Greece only after having learned his location from this page, please 'fess up when submitting your answer -- you still get partial credit for that.
You should be aware that your reasoning may be different from Holmes's. There are two unique and independent ways to determine from the evidence that the Sultan is in Greece. Perhaps only Holmes, with his forward-looking mind, sees the second set of clues. (Or perhaps you do....)