Amazing pictures, Fidd! Can almost touch the history there.
They do look very consistent with other wartime merchant ship pictures I've seen: grey and not particularly clean in appearance (but hopefully functional, as all equipment should be).
It's actually quite hard to find any pictures where wartime merchants would be sporting clean white paint on the superstructure. Nor can I see any examples of a black hull paint scheme like we see in Wolfpack.
I hope their appearance in the game is mostly a placeholder, hopefully to be replaced with more neatly textured models in coming patches.