The multiculturalist argument is that    diversity makes us stronger, and that we should celebrate its various manifestations equally at all costs. This has resulted in the absurdity of putting downwardly-aspirational gang culture on an equal footing with, say, the educational and self-betterment culture amongst Indians. Alongside this there is the cultural institutionalisation of a victim mentality which renders criticism of any group unacceptable.

There is, however, little real evidence to support the argument that diversity in and of itself is an unfettered social good. Quite the reverse. Robert Putnam, the Harvard sociologist who is hardly a right-wing zealot, concluded from his research that communal trust decreases the more diverse a society becomes — not just between different ethnic groups, but, interestingly, also within each of those groups.

This has all sorts of consequences, leading, among other things, to a lessening of the likelihood of working on community projects, a lowering of confidence in local politics, and indeed, less personal happiness. On the simplest of levels, if you cannot understand your neighbour, you will also feel (rightly) that you cannot take anything as given, or granted. Alienation (whether unconscious or not), and not a massively boosted sense of empowerment, is the natural and obvious outcome. 

Like everywhere else, Woolwich has been clearing up the mess left by the rioters, life has resumed, and the reasons for what happened will be pored over for months to come. But the public mood seems to have genuinely changed. Despite the steady stream of youth workers and community leaders on the airwaves in the immediate aftermath, the line that it was all the result of poverty, or government cuts, or the institutional racism of the police is simply not holding. There is some encouragement to be had in the fact that such platitudes are no longer accepted at face value, that even the usual suspects on the Left might have had second thoughts. 

The truth is dawning on the people of Britain that these riots were the product not of a strong, dynamic society, but an intensely fragile, deeply anxious one. In Woolwich, as in other inner-city districts, the damage has been done. There is no quick or easy way to make good the effects of 40 years of folly. The fear that was palpable on the streets of London this summer is here to stay.