To drift even farther off topic: I've noticed that people who do not have formal music schooling tend towards chromaticism, and make it work in interesting ways. Speaking of Pink Floyd, Syd Barrett didn't have any music schooling, and "Interstellar Overdrive" is highly chromatic. As are a lot of Radiohead songs-- no music school for Thom Yorke (Jonny Greenwood was the only member who had music training). I was stunned some years ago to find out that the progression of the verses of "Morning Bell" was A Also, a friend and I learned "Pyramid Song" years ago, charted it out, and discovered it's actually in 4/4: the phrases are highly syncopated but they add up to 8 (IIRC) bars of 4.

That's interesting - I Ran that song through Sonic Visualiser last year - and to me it seems as if the percussion is in 4/4 but the piano part repeats mostly over 22/8 (11/4) but sometimes 10/4... When I broke down the part into separate phrases I got 7/8, 6/8, 5/8, 4/8. I placed the output of Sonic Visualiser on a grid which seemed to match perfectly and given the name I am inclined to think that this is what is going on. It's a very interesting and contentious song and I could very well be wrong - but that is my theory