I am curious what we know about this song. We know that the the BBC 1970 rendition was faithful to the album version but by late 1970, it had evolved to the long-form arrangement as presented on BBC 1971 et. al. Where did this arrangement come from? It seemed to just appear out of the ether. The BBC book touches on it only briefly. Who composed the additions? If it were released in this form, would it be a G/M/W/W composition? A Gilmour / Wright one? I am quite fond of the long-form version and it is one of the reasons I really like the late '70 to late '71 period.
I'm not a musical scholar but I do note that The Who did something similar (expanding a routine 4-minute number into a 10+ minute opus) with Relax, as preserved in the 1968 Fillmore East recording. Was this sort of thing fairly common in this period? On another forum I was having a "get off my lawn moment" while talking about how I am unmoved by most modern music and one of the reasons is that I know of no active band who would even attempt a composition like this now. Perhaps this sort of thing was never common and I should be glad that anything like it exists at all.