A single lawful person with the will and the means to open fire would have stopped the UK pogroms in seconds. Mobs seldom loiter once repeating firearms are heard nearby…casualties among the rioters would have been instructive to their cohorts but probably not even necessary for ending the fiery mayhem.
As reality stands, the British Government insists that their subjects only go through the motions of self-defense without actual effect. That sounds like a very unhealthy fetish the UK Home Office enjoys at the expense of lives, health and property of others. In the US, rioters would probably fare better against police who just might use less lethal munitions than against regular citizens who would use conventional bullets. And a small loss would it be should the fans of arson, battery and assault come to grief at the hands of their intended victims.