OBC might be my favorite album by them, after WYWH.
It was one of two film scores for director Barbet Schroeder (after More, not as good, imo, the score, or movie it was based on). Unlike their later albums, which took months/years to gestate/compose/record/engineer, these were written and recorded very fast, which gave them a freshness and spontaneity perhaps never recaptured. If you think of Pink Floyd in terms of a band that was maturing very fast after Meddle into their iconic later sound exemplified by DSOM, documented in my favorite "concert" movie ever, Live At Pompeii (actually an anti-concert movie, in reaction to the increasingly bigger festival audience spectacles, such as Woodstock), OBC was recorded in several trips to France interrupting their DSOM sessions, so they were clearly on a roll.
Highly atmospheric Main Theme and Dramatic Theme from the score to More
* BTW, the late Storm Thorgerson's (co-founder of Hipgnosis, who designed most of Pink Floyd's covers - he knew the band back to Syd Barrett daze) revised edition of Mind Over Matter, a collection of Pink Floyd related art, came out recently and is a cool, oversized coffee table-type book, highly recommended.