Yeah, I like the clip, Lazenby
I'd also never connected those two pieces. Makes sense though... typically musician's have their own 'chord palette', that comes from habitual learning/ playing. I reckon it's why many musicians in later career stages find themselves battling against writing the same song again and again (and others just roll with it).
I like this kind of stuff as it makes sense of that whole journey between Piper and Dark Side. I used to think of much of 68-71 period as a series of misfires and a band struggling to reach it's previous heights (whilst liking bits and pieces), whereas now I think Gilmour and the others were already knocking it into a more refined (in traditional musical terms) thing in '68.
Although Atom Heart Mother possibly is my least favourite of all Floyd albums... I think the whole experiment with the orchestra etc ultimately produced a clunky, laboured sort of record.
I think possibly a relationship also between Narrow Way's D (A>G#) chromatic motif and Crying Song (Waters) > Opel (Barrett) > Brain Damage (Waters)? Or is that just a case of them all listening to blues?
