Conversation so far:
what were the orgins of this song?
McCartney, Harrison and Starr originally intended to record some incidental background music, as a trio, for the Anthology project, but later realised.
What did they realized?
according to Starr, that they wanted to record "new music".
What kind of sound is "free as a bird" inspired by?
CANNOTANSWER.
why is it called free as a bird?
CANNOTANSWER.

Question: who was involved with the song orginally?
Self-contained rewrite: who was involved with the song free as a bird orginally?