A last little tidbit about Oscar. I checked the German Navy Forum (which has everything you could ever want to know on the subject) concerning the Bismarck’s cat. Opinion seems to be mixed concerning Oscar’s existence, still, no one has proof one way or the other. There are posts, however, supporting the fact that mascots were present on many German warships of the era, including the presence of “one or two cats” aboard Bismarck.
Ark Royal is mentioned as having “several cats, all of which were saved when she sank”, though Oscar is not specifically mentioned.
The website of the HMS Cossack Association makes a definite declaration that Oscar was on board, having been rescued from the Bismarck. I may have to rethink my previous declaration about the validity of Oscar’s photo, however. The Cossack Association mentions it as being a newspaper photo of Oscar, and they should know. I have attempted to contact them to get what information I can. Stay tuned.