Ok, I'll make it simple - If England do well does it move Scotland, Wales and NI up the rankings?
No, it does not. But, that's got nothing to do with England winning being a good day for British sport. Prestige, image, positive impression etc are surely of some value regardless of moving up the FIFA rankings or not
If Andy Murray wins you wouldn't say it was a good day for Scottish sport because it doesn't move Scotland up the FIFA rankings?