If it looked like a fight was about to start, would I dial 999 or 112 or doesn't it make any real difference? (Didn't know which category to put this under.)
999 is the standard UK number but 112 will do just as well.
I used to be an operator and calls that came through on the 112 number could be sent over to the GPS team if they were on mobile to be traced for location. I don't know if that is still the case but if I was stranded on a hillside somewhere I'd definitely call 112.