The set in Buchan & Hall, The Scottish Folksinger was from Jimmy McBeath; very close indeed to Davy Stewart's. The word is glossed as 'meal', and the editors add "Often attributed to Besom Jimmy, an Angus hawker of the last [ie 19th] century."

There are some further useful comments, quoted mostly from Hamish Henderson, at http://mysongbook.de/msb/songs/c/comeally.html.

The attribution to 'Besom Jimmy' may only be anecdotal; but see http://www.banchory.org/cms/index.php?page=local_history for what is apparently a photo of him; if there was not more than one person by that name.