Early Brooks Racing Shirt

I got this one last year.  With the late starting zipper, bi-swing shoulders, one piece back, single snap collar with an unbranded snap, and cuffs which zip open, the consensus seems to be that it's an early Brooks, with a lot of Buco in the design.  Later Brooks jackets generally had two-snap collars, a kidney panel on the back, as well as larger panels for the bi-swing.