Move Change: notice closer to the bottom of the tune graphic. I was using \begin{center}..\end{center} to centre the tune graphic, followed by the change notice, if any. But this leaves a paragraph gap after the center section and hence a gap between tune graphic and change notice. Change to use figures to position the graphic, include the change notice as a caption, and use {\centering} around the image to centre just the image.

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\newpage
\section{List of tune first lines}

You know the feeling. Everyone has just launched into a well-loved tune.
You've heard it before, but don't remember the name. So here's a list of
tune first lines to help you figure out what it is in time to join in.

\setlength\LTleft{0pt}
\setlength\LTright{0pt}
\begin{longtable}{lr}