You could be right about the blue sky origins. But as sung mostly, I think think it means that on a beautifrul day like today, you'd need to be a slave to work, and I'm no slave - and that's subversive in a work-obsessed culture. Increasingly so in fact, and seen as subversive by the left and the right. (Willy Hague or Tony Blair, words they just don't like to hear)
So farSolidarity Forever has had a couple of mentions, but I think noone has put in its less respectable brother, The Red Revolution, with its memorable chorus:
Arson rape and bloody murder,
Arson rape and bloody murder,
Arson rape and bloody murder,
When the Red Revolution comes.