Thanks, Felipa - the link to the Beaton Institute is great.

The idea of a slow waulking song does make sense. After all, if sailors had capstan and halyard shanties, why wouldn't the tweed workers have something similar for their own slow stage in the waulking process?

It looks as if the song has a nice folk pedigree with one version turning up in the Gaelic Songster (published Glasgow, 1879) and another version found with an old Cape Breton fisherman a hundred years later.