"Song 2 (Roger's Boogie)"

I just discovered this song yesterday. It doesn't sound anything like Pink Floyd (besides the organ solo at the end). I can't even tell who is singing it (I think it's Roger?) The lyrics aren't Waters-esque to me (Lady ddivine, Gabriel came to the stable last night).

Does anybody have any information about this song? I'm kind of obsessed with it now--but it is just so un-Floyd-like and weird!

The only info that I have is that it's a Roger Waters song recorded in LA in August of 1968.