In the DEMS Bulletin 1982-3, there is a reprint of an article in which Irving Mills explains why he split with Ellington.
The headline says it all but it is interesting that Mills considered it a temporary split. “We will be reunited”, he says.
Mills told the story to a certain Charles Emge but DEMS does not say in which magazine it was published or when. However, it seems that it dates from the early 1950s.
Perhaps there are DESS members or other visitors to the website who have more details about the article. If so, just add a comment to the post.
The full article can be read here.