[GJO]

I asked a similar question a while ago and didn't receive an answer. I am guessing that the problem is that there wouldn't be that many targets!

After the sinking of the Bismark, there were very few enemy surface ships in the Atlantic - and whereas the majority of merchant ships would have been British or allied in the 1940s, German and Italian vessels would have proved very difficult to locate.

The best bet would have been the Mediterranean where Royal Navy submarines achieved some success against German and Italian targets. Also in the Indian Ocean where Royal navy submarines achieved limited success against Japanese targets.