Something that has always puzzled me - how is this song so well know?

I'm not trying to be all super indie here (I'm not sure I've ever heard the recorded version, just seen them play it a few times), but its tucked away on one of the really really early albums which I don't think is even in print anymore.

Given just how many songs he's written, why this song over basically everything else pre-4AD? Was it used in a film or covered by someone or SOMETHING?

Signed,
Puzzled of King's Cross