I was wondering if anyone can provide any information on this case. I tried looking up the reference numbers on the caseback and the only results that showed up were for an Omega Marine but that doesn't make sense.
I too suspect it is not an Omega.
From the patina and vibe, possibly from the WWII era( at a guess). I've seen a case and numbered caseback like that before, but I can't remember. Lemania perhaps ? ..others will know more..