Well, it took a while, but here we go.
First of all, as I mentioned I filtered out a resonance in the main vocal, I then widened the stereo positioning so it would like there are 5 distinct 'players' with just the main singer/guitarist in the centre.
I then had lots of fun trying to balance the levels - not easy when the parts are mostly in different parts of the spectrum.
As for adding anything myself, well I couldn't find anything that actually added to the song rather than detracting from it, so it's still all your work James