I was going to agree with Peter. The growth in lone-parent families is a long-term trend, not just in the U.K., but across Europe. You're absolutely right that one of the leading causes is financial stress. But I'm also dubious that reducing financial stress would reduce the rate at which lone-parent families form, because they form for a whole range of reasons.
One of the things that runs counter to that is that financial independence for women sometimes means that women who are dissatisfied in a relationship now become lone-parent households because they're not so economically dependent.
It's a complex issue. I don't think reducing financial stress would reduce the numbers of lone-parent households by a significant degree, although again it's a legitimate question.