Curmudgeon, I haven't read the new bio, but I have read much of the other MacColl literature, and you're off on some of the history. In the Essential Ewan MacColl Songbook, Peggy Seeger points out that Ewan wrote political songs for nine different factory newspapers in the 1930s (I've only found one in the book, from 1932...since there is no date index, it's hard to know if there are more in there!)

He also wrote songs like "The Plodder Steam" in 1939, "The Leader's a Bleeder" (about Sir Oswald Mosley!) in 1943, "The Second Front Song" in 1943-44, "Ivor" in 1944, "21 Years" in 1946, etc.

Given that he was a professional songwriter and actor by the age of 18, and a professional radio playwright by 21, I doubt if too many collectors would ever consider him a "source singer." We could, of course, argue at length about what that term means, but MacColl, like Bert Lloyd, learned at least as much about folksongs from books as he did from his family and community, even as a teenager (Seeger recounts that he spent most of his time during the depression reading in the Manchester Library.)

Like Lloyd, MacColl is situated in a way between the tradition and the revival--but he was never, I think, a "source singer."

I'll certainly read the book when I can!