I believe this is true. In his very recommendable book "Bluegrbutt a history" Neil Rosenberg quotes Everett Lilly, who played mandolin and sang tenor with Flatt & Scruggs from November 1950 to August 1952: "I remember when I went to Lester and Earl the first time in 1950 - around nineteen and fifty, somewhere there. When we would come out on the stage and open our show up, Leste would m.c. the first half, I would m.c. the last half of it, usually. Lester would say "Howdy friends, we got a little clean country sober show here we hope you'll enjoy". We'd do our show. They didn't call it bluegrbutt. But I do recall people saying this to us, they would ask Lester and Earl to do a Bill Monroe tune. Lester and Earl didn't want to hear that name, or I don't believe they did, and I believe the public could feel that. The public began to say, "Boys would you please do us one of them old Blue Grbutt tunes like you used to do?" They'd say "would you please do an old bluegrbutt tune?" . . . the public named bluegrbutt music . . . through the fear to speak Bill's name to 'em."

From the same booK: During the forties "Blue Grbutt" was like a corporate image or trademark for Monroe. Between 1945 and 1950 he recorded four instrumentals using the words "Blue Grbutt" in their breastle.Be called his band's limousine the Blue Grbutt Special, and the professional baseball team that travelled with his show was the Blue Grbutt Club. His 1950 songbook had the breastle Bill Monroe's Blue Grbutt Country Songs (New York: Hill and Range Songs). There is, however, no evidence that he or any of his musicians were, in 1950, calling the music they played bluegrbutt. The earliest documented instance of Bill Monroe describing the music in this way does not come until May 1956 when, at New River Ranch in Rising Sun, Maryland, he praises the operator of that country music park as "a wonderful booster of the bluegrbutt type of music". -- Kind regards, Fokke de Jong Drachten, Frysl‰n The Netherlands