You see it a lot around Manchester, I'd rather have more police than less police and it kicking off. I remember one team being escorted by the riot police to the stadium not long ago.
Lessons were learnt after an incident some years ago:
http://en.wikipedia.org/wiki/2008_UEFA_Cup_Final_riots
I remember it well, lived and worked in the city centre and it was not pleasant.
There is also a ban on alcohol sales at some stores in the city centre while some games are on, at least to footballs fans anyway.
It may be the police presence which is stopping any fans becoming "lairy". You could have been held up by a parade of lairy football fans anyway, in some games here groups of fans often parade around the city centre chanting and such which can cause issues with traffic flow, especially around rush hour.
I was in York last week and saw a number of rather mouthy Bury fans being escorted through town by the police. Even had a large group of boys (around 15 apparently) thrown off the train for being drunk and abusive to the ticket inspector.