Lyric discussion by epiwoosh 

Cover art for Sally B lyrics by Richard Thompson

These lyrics are somewhat mysterious to me, but they make me think of the character of Maria in Fritz Lang's 1927 movie Metropolis. She's a sort of messianic figure who is trying to educate the working class on how to assert their rights against the oppressive ruling class. It's hard to imagine a character like that would be the subject of a pretty straightforward pop song, even one by a generally non-mainstream musician like Richard Thompson, but I really can't think of any other logical possibility or explanation.