I reread the article and (IIRC) the upshot was that what is now the usual descending chromatic run in the B part was, in printed versions up to the start of the 20th century, repeated tonic or decorated versions thereof. The band versions added a chromatic descending bass below that, so that by the 50s (the time it became the Captain Pugwash theme - 57) this was common, and it was so in the theme, but the chromatic bass was quite prominent. Post Pugwash the chromatic descending run more and more often moved into the tune, which is how you usually here it these days. ("The tradition of playing it as before persisted with recording artistes who had learned the tune 'pre-Pugwash' and who for reasons of either aesthetics or habit did not alter their playing of the tune...Recordings made towards the end of the 1970s tend to show the more general adoption of the 'post-Pugwash' chromatic figure in the tune").

(And his favoured harmony for the last four bars is (in G):

G / G7 /|C / Eb7 /|G / D7 /|G / /||

)

Mick