Military Pocket Watch Identification

[essenbob]

Hi, this is my first post.I am a bit of a collector of military pocket watches, I have just acquired my first Rolex albeit the movement being a bought in one. I know a little about the military use for this watch and understand the military markings and visible marks on the movement, but I have no idea where the movement serial number is, can someone please help? I am guessing the watch is from around 1940 but would like to date it correctly.

Any comments on the watch would be most welcome.

The glass has some scratches, do you think its best

Left alone
Polished
Replaced

Hope I have loaded the images correctly

Thanks