Harold Macmillan's advice was to leave morality to the bishops. If the current Tory leader has ever heard that tip, he has decided to ignore it. Not since their suicidal Back to Basics campaign have the Conservative Party attempted some old-fashioned moralising - until this week's Breakthrough Britain report, assembled by their one-time leader Iain Duncan Smith. Whether it likes it or not, Easterhouse plays a lead role in this story.

When Jacques Chirac famously visited this Glasgow scheme on May 16, 1996, someone who lives there told me they were less surprised to see the President of France walking down Lochend Road than the man beside him, Scottish Secretary Michael Forsyth. As Scotland's heavy industries disintegrated and thousands were excised from the unemployment records and dumped on what we now call incapacity benefit, successive Tory governments seemed to be looking the other way. The sighting of a Tory minister in a Glasgow housing scheme attracted the level of interest afforded to a rare bird blown to our shores by some freak weather event.

Come 2002, IDS experienced his own "Easterhouse epiphany". When he now talks about "fractured communities" that are "blighted by crime, alcohol, drug addiction and debt", full of people in "dysfunctional homes, trapped on benefits", where unemployment has "almost become hereditary", it is a cipher for Easterhouse. This is odd in a way, because Monsieur Chirac came to Easterhouse not because it was a basket-case but because community-based initiatives were helping to combat social deprivation. In fairness to Mr Duncan Smith, he left Glasgow with a very clear idea of the way in which the many problems of many people living in areas of multiple deprivation combine to strand them in poverty; how the welfare state's safety net can become a trapper's net.

He also had a good idea of what worked (community-based organisations such as housing associations, credit unions, kids' and pensioners' clubs) and what didn't (government-led, top-down, imposed initiatives). His two weighty reports on the subject, commissioned by David Cameron, reflect both his understanding of how all these issues are connected and the way nitty-gritty initiatives that address specific local needs (such as cheap credit and good, affordable, flexible childcare) are the answer. Among the 190 recommendations, there are some eminently sensible ideas that Gordon Brown would be foolish to ignore.

It is up to the current Tory leadership to decide what to adopt as manifesto commitments in advance of the next General Election. The initial signs are not encouraging. Launching the report on Tuesday, Mr Cameron decided to deliver not a radical blueprint on breaking cycles of deprivation in a profoundly unequal society, but a paean of praise for the institution of marriage. The moral was that marriage is the glue that will mend our broken society. Gordon Brown has been making positive noises about marriage, too - but, as fumbling answers from Ed Miliband on Tuesday's Today programme illustrated, Labour is in a bind over knot-tying.

That is because our tax and benefits systems seem to send different messages to people on different parts of the income scale. At the top, the message is pretty clear. Couples who cohabit without marrying are massively disadvantaged when it comes to inheritance tax and capital gains tax. But at the bottom, lone parents on benefit or working tax credit are actually better off than married ones (on paper, at least). David Cameron proposes to sweep away what he sees as a perverse incentive to separate by allowing married couples to transfer tax allowances between them, if one parent is not working. This is not as generous as it looks. Worth around £20 a week, it would affect only around one million households - though, usefully, lots of them are in Tory marginals. An increase in the married couples' allowances would give 1.8 million of them an extra £32 a week in working tax credit.

However, it isn't just that these extremely expensive tax breaks for married couples are based on questionable logic. Their overall effect would be regressive, because they would disadvantage lone parents, who dominate poverty statistics.

Is marriage a better basis for child-rearing than co-habitation? Indubitably. The average marriage lasts 11 years, while the average co-habitation lasts only three. But there is a certain inevitability about this because marriage is largely a consequence, not a cause, of stability. People in stable relationships are more likely to get and stay married. Ergo, giving cohabiting couples tax incentives to marry won't magically turn unstable relationships into stable ones. Despite plenty of exceptions on both sides, it is also true that the children of married couples have better prospects at school and in the labour market. But beware of false correlations. Cameron's speech has launched another round of lone-parent-bashing. Bruce Anderson fulminated in The Independent: "Britain has the highest rate of single-motherhood in Europe, which is why we also have the highest prison population." Wait on. If lone parenthood causes poverty, why has Denmark, which has the same percentage of single parents, the lowest rate of child poverty in the EU? And, come to think of it, the lowest prison population?

The difference is that in Britain, and in Glasgow in particular, many of these lone parents are girls from deprived communities who embark on motherhood early because they have so little to live for and so little to lose. There are 28,000 lone parents in Glasgow; in Easterhouse they account for 28% of all households. The only way the state can prevent the children from falling into the same cycle of hopelessness is to reach deep into communities with properly funded and sustained initiatives, preferably delivered by locally-based organisations. That is why the rest of Breakthrough Britain is worth reading. But the last thing these women need is tax and benefits reforms that will make them worse off.

Also, do the Tories really want a change that would favour the philanderer on his fourth marriage over the trail of abandoned women left behind? What about widows and battered wives and teenage girls forcibly inseminated by local thugs? Cameron talks about progressive, compassionate Conservatism, but discriminating in favour of married couples looks more like a retreat to the bad old days of blaming the poor for their poverty.

It is just as unfair and perverse to reward better-off stay-at-home married mums at the same time as pushing impoverished lone mothers out to work. That is exactly what these proposals would do, by docking the benefits of lone parents if they failed to take part-time work once their youngest child reached five. There are many reasons why they find it hard to find and keep decent jobs, and for some work may not be the answer. Providing real support, such as flexible childcare and initiatives to steer youngsters away from alcohol, gambling, crime and drugs, is very expensive.

On Tuesday, David Cameron spoke of having to make "difficult choices". Reintroducing marriage bonuses would come in at about £6bn a year and do little or nothing to help the residents of communities such as Easterhouse. But many of the other suggestions in this report, such as expanding credit unions as a bulwark against loan sharks, and schemes to keep children out of trouble, could make a real difference. Cameron should follow Macmillan's advice on morality and go forwards, not back.