To draw a comparison from local history, the Cannon Street Riots. The cause of which was a someone being killed in a fight they provoked, the guy (an Arab) killed a white British man is self defence (or so the evidence suggests but its unclear), a mob descended on the Taj Mahal café on Cannon Street smashing the window and starting a riot.
Reports and testimony from that day shows that a significant portion of those rioting midway through are probably not aware and or do not care, of the underlying cause.
The historical question about that riot is its place in the historiography and its macro causations. Was it part of a series of riots in the 50, 60s and 70s, around immigration, increasing poverty and neglect of Northern towns?
What is interesting and where I feel the parallel to now exists, is race/immigration was often the flashpoint but the overall issues where greater. Often the racial tension was flared up and used as an excuse by bad actors to flare up trouble for their own ideological ends. They preyed on the situation and issues people of the time where suffering and gave them an "other" to direct their frustrations at.
I believe this is what we are seeing here, a forgotten underclass with little to no social mobility or prospects angry at the world and been told its all the brown people's fault.
Yes there will have been some "believers" of far-right ideology there, but a significant number were there because they are angry and given an excuse to vent that anger.
Just my opinion for what its worth.
(Edit to tidy up language at the start)