Look at a photograph of the crowd at the 1923 FA Cup final and pretty much everybody is wearing a hat. Fast-forward a quarter of a century and a rough estimate would be that a little under half the crowd at the 1948 final are similarly clad. Go forward another 25 years to 1973 and although Bob Stokoe, the Sunderland manager, topped off his tracksuit-and-mac look with a trilby, almost nobody in the stands at Wembley has their head covered.
In the unlikely event that anybody at the first Wembley Cup final gave the matter any thought, it is doubtful they would have believed bare-headedness would become the norm. And yet over the course of half a century, men stopped wearing hats. Things change, often unexpectedly, and aspects of life we take for granted can drift away, almost unnoticed.
