Cyclical with the general health of the game and how well we doing.there was a general increase in crowds in the late 80s n early 90s n together with a strong GB side rubbed off on the crowds v Aus.
From the mid 60s till the mid70s even periods of stong GB teams couldn't offset the secular decline in gates- lots of 10k n smaller gates v Aus
The only reason "swing low" is sung is because in the days of rude songs post match down the clubhouse it made for some good miming (especially at the "coming for to carry me home bit).in recent years thankfully you don't see the mimming actions
A lot of things came together in the early 60s to crunch gates down.From within the game the impact of more professional coaching on defence making unlimited tackle less attractive after the more open rugby of the 40s n 50s ,broader social trends changing peoples' leisure activities and so on.Personally I also feel the advent of Match of The Day had a big impact in widening the appeal of soccer.As a young boy in St Helens in the early 60s touch rugby in the street/playground/park was the default game.Ten years later and it was all football with rugby only happening on an organized school/club level.
I'm a keen Saints fan n laughed out loud as they showed it.It was completely appropriate given our woeful performance on a night when at they very least we needed to make sure the points difference wasn't eroded too much.