I don't know for sure if it was created when my family of distillers worked for Pappy...Actually, Pop Beam and Elmo worked there at the same time in the early days. I have a picture of them standing in front of the distillery. Hell, all of the "7 sons" worked for the VanWinkle family
I have a letter from Pappy sent to my Uncle Wilmer (Master Distiller, Yellowstone 1956). That letter was sent in regard to Pop Beams death. Pappy states in that letter that they made wonderful bourbon, with exception on the first day... That clue (in my opinion) told me that they were probably "inventing something" for Pappy He also went on to say that he was the Dean Distiller of his Age...
I guess it's something we will never know for sure.
Will McGill was my great Uncle. He was brother to my great-grandmother Katie McGill Beam