The composition of British society has changed so fast in the past 35 years that the term "traditional family household" is increasingly meaningless. The neat symmetry of "maw, paw and the weans" has given way to a mosaic of different household structures. Today, barely one-third of us live in such households, compared with more than half in 1971, according to the latest edition of Social Trends from the Office for National Statistics.

Over the same period, the numbers living alone have swollen from three million to more than seven million. And, as many couples delay parenthood and many others wave off grown-up children, there has been a steady growth in couples living without children. They now account for 25% of all households. But there is no doubting the biggest change of all: the rise and rise of the lone-parent family. In 1972, just 7% of children lived with only one parent. By last summer, that had risen to 24%. It is hard to understate the impact this statistic has, or should have, on public policy.

Lone-parenthood in Britain is more synonymous with poverty and disadvantage than practically anywhere else in Europe. A child growing up with a single parent is twice as likely to be poor. They are also more likely to live in substandard housing. If there is a single message to be drawn from this report, it is that successive governments have failed lone parents. Today, more than ever, they are caught in a cleft stick. The much-talked of "crisis in parenting" is often a thinly disguised attack on lone parents, who are expected to "be there for their children".
At the same time, government policy is almost solely focused on getting lone parents out to work as the only practical route out of poverty. It would be easier for them to square this circle if there were more good-quality, affordable childcare and if more employers were prepared to offer genuinely flexible working. Despite the barriers to work, lone parents can hardly be described as workshy. In fact, 56% of them are already working at least part-time and, in Scotland, the figure is even higher (59%). Alas, given the level of the minimum wage, many still struggle to get off the breadline.

Meanwhile, there needs to be more recognition that some lone parents are simply not in a position to work. For instance, more than a quarter of one-parent families include a child with a disability, another barrier to employment, especially when combined with inadequate childcare. Some of these households can only be floated out of poverty by better income support. More and better social housing would also help single parents more than any other group. As Scotland's political parties lay out their stalls this week with policies designed to appeal to all and sundry, they should pay special attention to those least able to help themselves.