The real lessons of this tragedy are twofold. One is merely tactical. All societies are vulnerable to lone-wolf actors: Norway's security services have failed to find any more self-proclaimed "Knights Templar" lurking in the shadows, or links with right-wing or anti-Islamist groups elsewhere in Europe. And Norway could have done more to frustrate Breivik earlier, when he purchased  fertiliser or reconnoitred Utoya.

The second lesson concerns a general failure to get to grips with the concept of populism, as distinct from Fascism and Neo-Nazism. Historical Fascist parties certainly made strong populist pitches, but the concept of populism is less useful to the Left, and not only because there are plenty of left-wing populists, from Hugo Chávez to his pal Ken Livingstone. Populism is a rhetorical style as well as an ideology. Most populist parties contrast the virtuous people with corrupt and cynical elites. The Danish People's Party, Sweden Democrats, Norwegian Progress Party and the True Finns all defend the welfare state, and are hostile to big business and the EU. But one issue mobilises such people like no other: radical Islam.

Although the European Left has undergone any number of ideological mutations, from Eurocommunism to New Labour, in its perpetual quest for hidden jackboots it never imagines commensurate transformations on the Right or a politics that transcends such divisions, despite the fact that many of its traditional working-class supporters are joining populist parties.

The new populist parties have subsumed the violent ultra-Right, along with many more people worried about an intolerant, homophobic, violent and undemocratic strain of Islam. That fearful constituency encompasses Christians, Jews, gays and what in the US are called "security moms". This kind of politics thrives in places like Scandinavia where immigration has been sudden, without the complication of a colonial past, and driven by liberal elites advertising their humanitarian credentials. The more politics is seen as corrupt and incestuous, the more what are disgustingly called "little people" will explore alternative avenues of representation. The Downing Street electronic petition on capital punishment is merely a grotesque version of this phenomenon. That is a more troubling prospect than whether mad and bad men like Anders Breivik come along from time to time. Rather than vacuously calling for more investigative resources to be devoted to the "far Right", David Cameron should reflect on his own contributions to these problems.