... so, I looked around for something more substantial
about this business of a manuscript/lyric sheet
left in a taxicab.

What I have discovered is what looks like
a cross between a journalism report and a dissertation,
which confirms that
many contradictory reports exist about this
"Joe Clumsy left it in the taxicab" story.
The closer you look at it all,
the harder it is to sort out --
this song's history gets
really murky in places!

And I still don't know how to account for
"the alternate lyrics,"
as sung by Helen Morgan amongst others.

Another confirmation regarding
the lyrics in the OP.
Those lyrics begin with a verse,
then proceed to the chorus.
And that verse is indeed sung by
Elsie Carlisle, I believe she was English.