Has anybody ever established what Shrewsbury were singing to that tune that night?
Are Shrewsbury even aware they had a song to that tune?

Wouldn't surprise me if whichever Notts fan came up with it misheard the tune also and not just the lyrics, being worse for wear and his mates thought it was funny and it became an in-joke for the next match.

It was the group at the back of County Road Stand next to the seats who started singing it v Cardiff at ML, but only a handful of them. At that point it was as self indulgent and esoteric as the "Let's all batter Seagraves" chant (Seagraves being a member of that gang) which would usually follow "Let's all have a disco". Presumably it was Birmingham away (where we won 2-1 in the game that followed) where it gained some traction before the memorable 3-1 win at home to Bristol Rovers. It would have been that Bristol Rovers game or the Bolton SF where it properly took off in time for the Wembley final.