Having been informed that band actually aren't Tangerine Dream, but Kaleidoscope. So...
Kaleidoscope - The Sky Children, 1967
http://www.youtube.com/watch?v=0dQOJ657ptE
The first of my essential songs not to be a single release, Kaleidoscope's 'The Sky Children' is the final track from the groups 'Tangerine Dream' album. (edited to get it the right way around!)
Come to this record with even the slightest trace of cynicism and it'll float away in front of you, but embrace your inner-hippie and it'll lock in to your brain forever.
Here's a brief review from Marmalade-Skies, my go to site for all things British Psych:
My favourite Kaleidoscope track of all. Almost eight minutes of music that once heard is never forgotten. Eddy, Steve and Danny lock together in an egoless display of teamwork, the like of which is rarely heard in pop/rock music. This leaves Peter with freedom to deliver his torrent of words, and deliver he certainly does, with an astonishing vocal performance of intimate beauty. The lyrics--inspired by the view from a cliff-top in Swanage--are full of stunning imagery and child-like (but never childish) wonder. Let your mind fly along with the children, dream their dreams with them, discover the part of yourself that remains child-like (it's in all of us somewhere).
Anyway, It's arguably the quintessential 60s British Psych record, and it's my essential song #5.