Thanks for the links, Snuffy. It's hard to explain why, but I find the mentioning of specific brand names in this song adds significantly to its humor. I think the term for this is "bathos"—not a word I use often; in fact, I think this is the first time I've ever used it. Just to be sure I was on safe ground, I looked it up: "An abrupt, unintended transition in style from the exalted to the commonplace, producing a ludicrous effect." Fine, but I'm sure the effect was intended in this case—intended by Harry Clifton, that is, not by the fictional narrator.