If they've amalgamated, Les, I wonder what their official 'marchpast' is now 'My Bonny Yorkshire Wellingtons'?

Walrus.
Course it is. The question remains, did the football fans get it from the advert or from the playing of military marches by brass bands in the intervals.

I'm still intrigued by the reference to 'The Old Grey Mare'. As I said I know lots of 'Old Grey Mares' (No cheeky comments please) but none of them would fit to the Caissons tune.
The most obvious American OGM is 'The Old Grey mare she ain't what she used to be, many long years ago.'