its pretty self explanatory really how these things happen, it goes on in every town in England, the quiet nice life and trouble free pubs and clubs you describe is far more uncommon than what really goes on, can you truly say you have never been in a situation of having to defend yourself while out socialising or anywhere really?
not in the last 30 years mate.
If someone approaches me for a fight I would just tell them they can fight me and I will shake their hand and enjoy the rest of my night.
I dont frequent place where there is a high probability of violence, last time I was out and a fight broke out I made my way back to where my Mrs was and sat down and let the doormen do their job.