Despite walking up that road and seeing nothing, I'd bet my house that the "City fans spat on a woman" line is a classic, common-or-garden British lunge for the moral high ground.
The incident will have started with some singing/verbals and escalated into a bit of handbags. Somebody might have spat, or thrown the contents of a can or something, and of course what your standard Brit does is this: think of the worse-case-scenario for moral outrage, and leap at it. So if a woman, or kids, were in the vicinity, and they will have been, point them out and say "There's a woman here!" and act all outraged. Then the story is simply and quickly spun to "City fans were spitting on women".
Moral Highgrounding. The English Disease. After people have spun it and repeated it, they generally start to believe it, too. The other week I went for a piss at half time in the top tier bogs in the Colin Bell Stand. Usually loads of people stand down the spirals having a fag. The club have obviously had enough because they'd put temporary barriers up, manned by stewards. Some bloke was absolutely gobbing off to these stewards "What if there's a fire? This is illegal! What if there's a mass evacuation? Get the manager here now!" and all this. He just wanted his fucking half time fag, but he'd immediately and instinctively adopted the moral high ground and wasn't budging from it. Everyone's at it to try to get their own way.