The British lower classes, like those elsewhere, have for a very long time expressed their grievances with riot against the established order, going back to the Poor riot of 1196, and including the Spitalfield and Gordon riots of the 18th century, the Luddite and Bristol riots of the 19th century, and the Luton Peace Day riot of the 20th. Other Western countries have similar histories but, with the exception of the United States, seem to have in recent times achieved greater success at relieving tensions in the social order.
One reason, perhaps the major reason, why social distrust smolders in Great Britain is the persistence of inequality, of class, in that country. Despite considerable progress, Britain remains one of the most inequitable nations in the West.
Inequality can be measured in various ways, but the results are much the same. Consider, for instance, the ratio of the average income of the richest 10 per cent of the population to the poorest 10 per cent. In the more equitable Western countries, that ratio runs at around six (Norway 6.1, Sweden 6.2, Germany 6.9, etc.). For France and Canada, it is higher at 9.1 and 9.4 respectively. Britain's ratio is 13.8, exactly twice that of Germany and almost as bad as the United States at 15.9. The class struggle persists in that green and pleasant land.
We know that inequality in a society equates to dysfunction. The higher the inequality, the less healthy a society is—the higher the rates of crime, drug abuse, mental illness, etc., and presumably the more susceptible it is to rioting. Prime Minister David Cameron can preach moral values until he's blue in the face but until Britain deals seriously with its inequality problem, i.e. its class problem, it will suffer a relatively high rate of social tension, the next riot just around the corner.