Why did he adopt a stage name?
I am aware of how he helped others, and I booked both of them at a folk club and did a support for them.
WIKI In 1946 members of Theatre Union and others formed Theatre Workshop and spent the next few years touring, mostly in the north of England. In 1945, Miller changed his name to Ewan MacColl (influenced by the Lallans movement in Scotland)
So it might appear it was more to do with his career as a playright than as a singer?