My apologies for not yet having returned with more detail. Michael kindly sent me the Kidson article and I got rather bogged down chasing up further examples of the tune as used for versions of 'The Foggy Dew' (there are several such). My impression is that Kidson's comments have been misunderstood by some later writers, partly due to ambiguous use of punctuation (for 'a variation having Irish characteristics of "Ye Banks and Braes"', read 'a variation, having Irish characteristics, of "Ye Banks and Braes": it makes quite a difference) but I will have to revisit all this later once current deadlines are safely past.