I used to work in a town where the school had a large (very large) number of Romany, Irish traveller and Roma children from the locality. Whenever there was a funeral for any of these groups the town ground to a standstill because of the huge numbers that would turn out to said funeral.
If staff wanted to get home they had to go out of the other end of town. I seem to remember that the schools and pubs were all notified (not warned) of the time and place of the funerals so that those who wanted to close could do so.
Nearer London I can imagine that traffic chaos would ensue, people trying to get places would be delayed and get frustrated and a few hotheads could easily start an affray which opportunists could quickly inflame into real trouble.
Adding alcohol into the mix just makes the likelihood of trouble greater.
Folk organiser sounds pee'd off rather than racist in this instance.