This is a lovely atmospheric song with three chords.
Those Island Years! Black Man At Your Shoulder instrumental from the long version.
Found on the promotional Dancing 7'' single. Ripped by some legend on a torrent site, uploaded for you here.
Thanks to Kipper1999 and Ian McGeachy for their Tunings. I've tweaked it a bit and ended up with C G D# F A# D which I think goes with the Live at Leeds ...