The last few posts to this thread really help us determine the maker of Farmer's jacket, but I'll try to explain why I harped on the oxy tab. The first two pics show my B-15D Mods, maker unknown but I strongly suspect Rolen Sportswear based on photos of originals. Note how the leading edge of the tab is left unfinished, which differs from that of known MA-1s, Farmer's jacket, and George's Lion B-15D. Note also the leather puller tabs, as opposed to the strip of cotton webbing used (to the best of my knowledge)
exclusively by Lion Uniform:
Here are two shots of an unmodified Rolen B-15D, showing the unfinished leading edge on the oxy tab. Note also the cotton webbing hanger loop in the photo at right, which is identical to that of one of my jackets:
Here's the oxy tab of a Skyline 8279, but every other early MA-1 in my collection is the same. Here the leading edge of the tab is folded over and stitched, presumably to prevent the clip attaching the oxygen mask to slip off unintentionally:
The upshot of all this is that Farmer's jacket shows all the hallmarks of a Lion Uniform product. The wind flap, oxy tab, and Crown zip with cotton web puller are all telltale signs of the maker. However, as Danny pointed out earlier we'll never know which model it is without seeing the label . . . :x