Leading article: Mr Cameron road-tests the politics of responsibility

It is a brave politician who utters the words "personal" and "responsibility" in the same sentence, and an even braver one who, without wincing, adds "morality". But David Cameron knew exactly what he was doing in Gallowgate this week. He was careful where care was needed and bold where he meant to be bold. He also neatly avoided the trap in which John Major's "back to basics" agenda was crushed, conceding that politicians were "as likely to screw up" as anyone else. Never let it be said that politicians do not learn from others' mistakes.

From there it was relatively plain sailing into the delicate matter of good and bad, right and wrong. He did not go so far as to deny the existence of society, but he did argue that social problems were "often the consequences of the choices that people make".

The Conservative leader's decision to make Glasgow East the "broken society by-election" is a smart move in every sense. The party has not the slightest hope of victory here. It can afford to test the electoral appeal of some straight talking. It was also a stroke of luck for Mr Cameron – a politician who has been as blessed in this respect as the Prime Minister has been cursed – that this crucial by-election is taking place in the very constituency where Iain Duncan-Smith experienced his epiphany about "Breakdown Britain".

Unlikely as it might once have seemed, places like Gallowgate are now familiar territory for Cameron Conservatives. And the more benighted the estate, the more grist it provides for their policy mill. "The social breakdown you can see here," Mr Cameron told his audience, "is just an extreme version of what you can see everywhere." And "everywhere", of course, is the country that was once Blair's Britain and is now the responsibility of Gordon Brown. From there on, Mr Cameron's rallying cry writes itself: "Wasn't Labour supposed to end this degrading poverty?"

The gritty urban backdrop of Monday's speech provided the most graphic illustration to date of how successfully Mr Cameron has managed to seize the initiative on social policy from Labour. It is a feat reminiscent of the Blair-Brown coup of the Nineties that made New Labour the party of the economy and law and order. Coincidentally, much about this new Conservative agenda chimes with the increasingly grim public mood. Today's cause for agonised introspection may be knife crime, but few regard it as an isolated phenomenon. Teenagers armed with knives can be seen as a cypher for Labour's failure after more than 10 years in power.

Mr Cameron's appeal to such – recently – unfashionable themes as personal responsibility and morality will also strike a chord. After all, so much else seems to have been tried, yet social mobility has ground to a halt, the gap between poor and rich has widened and the Government is nowhere near meeting its target of halving child poverty by 2010. There is ample political space here for the Opposition to occupy. Yet the Conservatives will have to tread carefully. Mr Cameron's words were carefully crafted, but his party must be wary of sounding like new Victorians. To counter this, Mr Cameron alluded to the latest sociological fad – the theory that peer pressure can "nudge" people to behave better. The big test, of course, is whether the policies can match the salesmanship.

Mr Cameron spoke of radical plans to reform schools, improve housing, strengthen families and make state benefits more conditional on work. But it is not just, as he concedes, that such policies will come up against entrenched interests; they will have popular appeal as well. It is that coaxing the workless into work can cost more than underwriting idleness. This is where morality meets economic reality. The Conservatives may be on to something here; but they have more work to do.