It’s just drunken fuckwittery by useful idiots.
I am always amazed that at every single one of these events, they always manage to get the money shot of a police car (a bus in the case of Harehills) on fire. It’s if they’re just left there on purpose for people to torch. If I were a Chief Constable, I’d be saying “any of you leaves another patrol car to get written off, it’s coming out of your fucking pay”.