Has anyone come across this
ebay listing defined as follows?

Quote:
Interesting Envelope for Stamp Collecting by Engravers. Robert L. Miller worked for the US Bureau of Engraving as a Stamp Designer. This Unauthorized Airmail Cover was found in a prominent US Postmaster's Collection. Slogan Cancel is from Washington D.C. and is authentic (this was sent through the mail!) This is not a movie prop piece. You can see R.L. at the bottom of the plane but I was unable to find out what the "P" at the Lower Left Corner represents.This may have been one of his original designs that was never selected. Amazing Airmail Oddity from a Famous Stamp Designer.
http://www.ebay.com/itm/US-Unauthor...161721558460An expensive "oddity" to be sure, but the fact that it would seem to have made it through the mail makes it even more interesting, especially since there's no indication that it was "U.S." POSTAGE, as only the term "POSTAGE" was included in the design.
Do you think it's a genuine sketch of some preliminary design? It looks to me to be a rather crude design similar to the UC16 "letter sheet" from 1947.