I've found the quote from David, eventually. Here we go:

"'Shine On' is my favourite song from the 'Wish You Were Here' album. I thought I would try it solo with acoustic guitar. The record has the sound of fingers on wine glasses with keyboards on a long, drawn out opening, so I had to devise a new way of doing it. It struck me that there is a device I've used with a long repeating delay on my guitar with which I can give myself what sounds like a synthesised orchestral background. I found that it lent itself to it very well."

__________________
"Don't you know there ain't no devil, it's just god when he's drunk." Tom Waits