I see where you're coming from- and you're right, things will of course be different. But in my mind a group of people saying (or indeed shouting) something like ''hey!'' ''stop! i wanna speak with you!'' who have just got out of a vehicle driven by a 15 year old (min age is 18) is indeed aggressive and when followed up by ''go a head, ride away you pussy!'' (which would imply they wanted to hurt him- a threat) could be classed as affray, attempted assault and disorderly behaviour- the second allowing for the WPA to come into effect.
In this case, since OP is actually the victim it would allow for protection to be granted more easily. Keep in mind protection doesn't have to be armed police or body guards stood outside the door, but more things like emergency/panic buttons carried on the person, CCTV, monitored doors etc.
I deduced attempted assault by the way it was described (it may not be the case that it was).
EDIT: Like I say- this is our method of dealing with such situations, it probably won't be the same over there.