Got an interesting email today. This guy appears to have the original painting used for the IRE magazine cover. He bought it at an auction years ago and had no idea what it was (or why the row of little pennants) until he read the article on my website.
He says it's done with gouache on illustration board. On the back it is stamped "Associated Freelance Artists" from NYC, with another label that appears to order halftone color prints.
I asked him if he's able to provide a better quality photo, which would make a nice footnote for the article. Incidentally, I did eventually get my hands on a copy of the IRE magazine (thanks, John!).
Phil Nelson
http://antiqueradio.org/index.html