They just don't make them like this anymore. It's always a real joy to find one of these since we grade about 1,600,00lbs for each pre 50s jacket we find. Thick steerhide leather, conmar zips, flannel lining and a label still intact! This is a typical jacket of the time, sharing design clues with jackets like the Buco J23. Unfortunately, the label is too obscured for me to be able to tell the maker. I'd love to learn more about this, please leave a comment if you have any idea who the maker could have been.
As always, here's the label for your viewing pleasure (good luck reading it!):