I love, lovey, love this song. HILARITY. It's so Flanders and Swann. (And also, Armstrong and Miller's tribute act to Flanders and Swann.)
My favourite bit actually comes after this in which he explains that there are three types of people who react to the song; 1. musos who think it's the funniest thing ever, 2. normal people who are all 'heh, yeah, it's amusing I guess', and 3. people who can't hear anything wrong.