My copy of 'The Lasses Fashion' came without booklet, so if anyone has got it I'd be interested in purchasing a photocopy (at a reasonable price ...). The sleevenotes merely say:

[1982:] A ballad concerning the "disgusting courtship of two hideous giants" and which surpasses a lot of erotica for grossness. (Notes Jock Tamson's Bairns, 'The Lasses Fashion')

Some more notes:

[1966:] We may therefore surmise that another, and possibly very potent, cause of fracture [in tradition] is social attitude. Now, the outcome of a shift of attitude toward the subject matter of a ballad can be called loosely parody, and a number of varieties of parody may be distinguished. [One is] burlesque. Since burlesque normally consists of exaggeration, it will be likely to stay sufficiently close to the original to make the contrast vividly part of the fun. It can be regarded as a kind of practical joke at the expense of an original on which it is patterned. [...] Of course it by no means goes without saying that the author of a burlesque despises or dislikes the object of his sport. But he must be so far detached from it in spirit as to be willing to see its tragedy or high romance travestied from time to time without psychic recoil. Such psychic detachment is alien to tradition, which typically accepts without criticism what it passes on. [...] We may conjecture that a similar cycle [of alienation] has occurred in the case of[, among others,] Kempy Kay (no. 33), where, however, the originals vanished without being recorded, and only their mockeries have survived. (Bronson, Ballad 266f)

[1973:] [This is] a broad burlesque of the loathly lady theme that occurs in The Marriage of Sir Gawain (Ch 31) and King Henry (Ch 32). (David Buchan, Ballads 223)

[1976:] It seems that fifty to a hundred years ago there was a tendency among some scholars and others to attribute the exotic in traditional song and balladry to a Scandinavian origin. Alternatively, as many songs as possible - and a few beside - had Arthurian origins postulated for them. (Britannia with her growing Empire doing homage at the shrine of this mighty long-dead warrior. Certainly the romantic imagination was caught by this ragamuffin warlord and his band of Romano-British cast-offs.) C. K. Sharpe, in his "Ballad Book" (1823), seems almost to suggest both origins for Kempy Kay: "This song my learned friends will perceive to be of Scandinavian origin and that the wooer's name was probably suggested by Sir Kaye's of the Round Table [...]". King Knapperty is basically the version from Peter Buchan's MSS printed in Child's "English & Scottish Popular Ballads", with interpolations from other sets, and is the story of the wedding of the queen of all sluts to the king of all slobs. (Notes Martin Carthy, 'Crown of Horn')