Thanks Bob. I was hoping you would come through with some information.
I first heard a live version of the song on a radio programme David Mullhullan(?) used to have on Radio National on Sunday nights back in the late seventies/early eighties, and I was really taken with the alternate view the song portrayed.
There's a couple of words I've had to guess at; particularly the word "playing" in the middle bit:
And we saw small boats come sailing
from ships far out to sea.
And the shells came at us, playing
an infernal symphony.
Your advice would be appreciated.