Instrumental track fuelled by jazz music in general, and more specific that of saxophone player Pharoah Sanders. At first John tried to master the saxophone but then he modified his guitar in order to produce the desired sustain and distortion.
Glistening Glyndebourne and especially Outside In are clearly inspired by Pharoah Sanders' Red, Black & Green from Thembi (1971).
Not everyone picked up on the unusual echoplex sounds, by the way. Some critics called it 'rambling'. That's why they became critics.
By the way, Rob Young claimed as late as 1998 that the song Solid Air were based on the spectral chord shifts and tremolo-Fender Rhodes licks in Pharoah Sanders' Astral Traveling, also from Thembi. The track precedes Red, Black & Green. Young:
Martyn denies knowing the Sanders tune, and seems genuinely amazed at the comparison: 'I never thought of that. You could be right. That's interesting - I'd like to know which came first, the chicken or the egg? I probably just beat him to it [in fact, Thembi predates Solid Air by at least two years]. Is it in C minor? I'll kill him!'