England, from what I understand, has pretty strict speech codes and anything that can be perceived as offensive or threatening is grounds for arrest, trial, and fines and or jail.
England could finance their health care system for a decade if they enforce these laws on the Islamic Terrorist meeting.
I'm thinking that they could take care of this rally in two easy steps. First, announce to all of the soccer fans that there is going to be a soccer match between England and some especially hated opponent, with free beer for all who attend.
Second, schedule this match for the same time and place as this Muslim rally. And give the police the day off.
Problem solved.