[Puster Bill]

I should also have mentioned that you don't need to actually break the other guy's codes to get this sort of information. You can get it from basic traffic analysis and HF/DF. Here is how it would work.

Admiral Goodbloke (He really is a good bloke!) on the SS Feathersword* sends a message in code at 19:00Z. Several German DF stations get bearings on it, and the position is gridsquare XYZ. Then, 8 hours later, he sends another message. He is then DFed in gridsquare XMQ. We know it is the same ship because we have studied the British callsign system. Gridsquare XMQ happens to be approximately 54 nautical miles southwest of XYZ. We now know the approximate course (Southwest), and the approximate speed ( 54 NM / 8 hours = 6.75 knots), along with his approximate current location.

You don't even have to know the actual callsign rota, as every morse operator has a distinctive way of sending, known as a 'fist'. A good dittybopper can recognize this and know that a particular operator didn't teleport from one ship to another in the space of a few hours. The 'fingerprinting' of individual transmitters was also known in WWII, and is another way to tell who is who, although I am not sure if the Germans did that or not.

The information that you would get from this kind of intelligence almost exactly tracks what you see in SHIII, as DFing is rarely precise enough to give you exact locations, so that "Slow, Medium, Fast" is appropriate speed-wise, as are general compass directions instead of precise numeric headings.

*Give me a break, I have a toddler at home.