Yep, I don't remember when the St George's cross became so prominent at England games either. This is England fans in Turin during Italia 90, a lot more Union flagging:
November 20th according to Google. I think he has the advantage of having been a real person who lived in what is now England, would be unique to England (where George is shared by many), and he was the original patron saint. His flag is a dragon so I'd also like to see what Nike did with that...
There's a bloke in Lewes who flies the flag of St Edmund in his garden, England's original patron saint before he was usurped by George. I wonder who'd win in a saint-off?