"Why not" is part of VERSIONS of the Composition project, which maps out the creative process for a set of 14 compositions.

The series include the following titles:

Around and around
Couldn't be better
Count on it
Funny you should say that
I just can't remember
May's dance
Never so easy
Now make a wish
Pretty late
Prosecco
So sweet of you
Song bouncey
Why not
Wouldn't you love to know

Each title's finalised compositions and tunes are accompanied by their earlier draft versions as well as logs documenting differences between these drafts.

https://research.gold.ac.uk/id/eprint/10659