You'll Never Walk Alone (Carousel 1945; Gerry and the Pacemakers, 1963) is a fascinating example of the invention of tradition https://www.theguardian.com/music/2021/jan/04/how-youll-never-walk-alone-came-to-define-liverpool-fc-spirit-gerry-marsden#comments
In a parallel universe, could Anfield have ended up adopting one of the Beatles songs instead?
Bill Shankly chose it for Desert Island Discs in the run-up to the 1965 FA Cup final, and the fans can be heard singing it at Wembley (in the earliest known TV footage of it being sung on the terraces)
Kenneth Wolstenholme's cup final commentary suggests it is already familiar - as a "Liverpool signature tune". (The television cameras were at very few games in this era)
Shankly's Desert Island Discs (1965) https://twitter.com/JemStone/status/1346155245781573632