How uniform and capture circumstances would have shaped Canaris's status

Would Canaris have been treated as a spy or as a prisoner of war if Britain had caught him in Plymouth?

His status would have depended heavily on whether he was caught acting clandestinely out of uniform or identified as a uniformed naval officer.

The exchange turns on how Canaris would have appeared if British authorities had caught him during his passage through Plymouth. Out of uniform and acting clandestinely, he could have been treated as a spy and threatened with execution. In uniform, his position as a German naval officer would have supported treatment as a prisoner of war. The distinction matters, although the scenario remains counterfactual because Canaris stayed aboard ship and was not captured there.