Thanks for your reply. I have uploaded higher res pics. It could very well be that the case does not belong to the watch, but was just used to store it. As far as the engravings are concerned, these could be just ornamental. However, the letter left of the 12 could also be interpreted as a "G", and the one right of the 12 as an "O". Or is the left letter just a mirror image of the left letter?
As you can see there is a "P&B" stamped inside the watch. What could this mean?