Lyric discussion by WolfTickets 

First, I'm pretty sure the "workers have struck for fame/cos Lennon's on sale again line" is a slight jab at John Lennon, because a bit before <I>Hunky Dory</I> came out, Lennon put out his first real solo album, which included the proletariat-anthem "Working Class Hero", so Bowie's joking that, since Lennon is back, there's going to be a revolution.
As far as the song as a whole, I tend to see it as a commentary on the blurring of the line between art and real life: the girl has lived the movie, Bowie has written what is happening to him, Lennon's working class song will cause a working class revolution, etc, and i think the "Is there life on Mars?" line means, you know, we've made so many movies and TV shows and songs about aliens, so are they as real as the other things we write and talk and sing about?

Working Class Hero is a "proletariat-anthem"?

You're just f*****g peasants as far as I can see.

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