Let's discuss this weird little snippet from Smile...

[willy]

That little vocal snippet at 3:20 — the first few notes at least — is reminiscent of 'Prelude to Fade'... 

Already noted above.

Ah so it is... 

[buddhahat]

It sounds very much like a prototype for prelude to fade to me too. The first thing it reminded me of was the slow bit from rhapsody in blue which we know brian was into at the time. I always hear prelude to fade as brian's attempt to create a similar part for h&v and this is quite possibly an early stab at it.