I quite agree that bagpipes don't roar, Steve, and they don't usually come as a pair for that matter, but then I also doubt that willow would last long enough in a forge for the blacksmith's blowpipe idea to have much credence either. It is a set of words that has puzzled me (off and on) for years, and to not much effect.

What I do like is the "Twankydillo = (sound of) smith at work" theory. The rhythm to which it is sung matches what I have observed of smiths at work - strike, double bounce of hammer to side, strike, double bounce, etc. It just seems to make sense, which is, of course, no reason to believe anything.

Reading the early part of the thread, it is a joy to see that I am not alone in seeing the bawdy possibilities behind the versions I first heard sung. I expect that the performance, body language, eye rolling and the like, would be tailored to suit the singer's perception of the audience's sensibilities: no change there, then. Also good to learn Malcolm's missing verse; it seems appropriate, and a fairly short song can benefit from a little restoration.