Presumably, anyone who has read Simon Callow's HELLO AMERICANS knows that Orson Welles hired his good friend Duke Ellington to write the music for a planned early segment of IT'S ALL TRUE, called THE STORY OF JAZZ. The segment never ended up in the unfinished film, but Welles apparently placed the Duke on a salary of $1,000 a week, for which Ellington never wrote more than 28 bars of music!
Was that the end of Orson's collaboration with the Duke? No, because I just came across this article in BILLBOARD magazine, of December 11, 1943:
ORSON WELLES AND DUKE ELLINGTON TRY TO SELL MOBIL GAS
(New York - December 4) The combined talents of Orson Welles as the emcee and Duke Ellington as music maker were featured in a variety show auditioned at Compton Agency last Thursday. Although no time is skedded definite plans are expected by the end of the month.
Rita Hayworth and Jimmy Durante guested on the audition record as single shots. Jack Johnstone directed.
___
In other words, somewhere out there may be a "test" recording of Orson Welles and Duke Ellington, with guest stars Rita Hayworth and Jimmy Durante. Where is that fabulous treasure trove of Welles's radio shows, THE MUSEUM OF ORSON WELLES when we need you?

