Brewster Buffalo prototypeIn November 2003 I got email from Roy Berkowitz, who identified himself as "son of Samuel M. Berkowitz, who was the chief designing engineer of the Brewster Buffalo." Roy went on to say that his father "worked just north of Philadelphia for Brewster. I have a great old photo of my dad with one of the very early prototypes (NX147B) from those days."
Here's a reduced image of that photo, which as you can see is a bit wrinkled and also a bit of a parallelogram, so the edges are at a slant. I see from Jim Maas's Squad-Signal book about the Buffalo (p. 22) that this is Royal Air Force Buffalo W8131, completed early December 1940. It's a Model 339E with "armourglass" behind the windscreen and a ring & post sight that will eventually be replaced by a Mark III optical gunsight. "The white civil registration," Jim wrote, "is a temporary marking carried for flight tests and acceptance trials."
I assume that the airfield is near the Warminister/Johnsville plant that Brewster built near Philadelphia.