David Cameron has been in Stockholm this week, expressing his love for all things Nordic from economic openness, to free schools, and the Danish TV series The Killing.

Based on his pronouncements today he's doubtless also been attracted to Borgen, the political drama in which a female prime minister juggles coalition politics and the demands of a young family at the same time as driving through her commitment to equality in the corporate boardroom.

It's a welcome sign as we have a lot to learn from our Scandinavian friends -- and not just about increasing the number of female directors. We could also learn a lot when it comes to supporting the vast majority of working mothers.

As a new report from the Resolution Foundation today shows, motherhood in modern Britain still carries a heavy price in the workplace. More than nine out of ten of those surveyed, switched from full-time to part-time work since having children. Of course, for many women this is a positive choice with mothers wanting the flexibility to work fewer hours, especially when their children are young.

But here's the rub: it also shows that even when making a positive choice, working part-time still carries a very heavy cost. An incredible 44 per cent of women reported that they'd had to take a lower-skilled job when switching to part-time work.

By working part-time, do you feel you've had to take a lower skilled job than you would have if you worked full-time?

And while these trade-offs affect people in all income groups, those on low to middle incomes are far more likely to face constrained choices and tougher penalties. Compared to more affluent women, those on low to middle incomes are almost twice as likely to feel that they have no choice but to work part-time, and when they do they are 33 per cent more likely to be forced to take a lower skilled job.

Millions feel constrained, having to choose between a more fulfilling and well paid career and family life. As one respondent put it: "I guess just have to accept that career progression is impossible now because I chose to work part-time, employers won't admit it but this is the reality for part-time working mums."

And we're not just constraining parents' choices, we're also harming our economy. Overall the UK ranks 15th in the OECD in terms of levels of female employment. If we caught up with the highest performing countries, up to one million more women would be in the workplace.

The chart below shows the gap between our female employment rate and better performing countries for women of different ages. The story is clear -- it's at the peak years of childbirth that we really fall behind, with mothers having to drop out of the workforce.

Female employment gap between UK and better performing countries

Given that the UK has the second most expensive childcare in the OECD this is hardly a surprise - nor is the fact that almost half of working mothers say that the lack of affordable and quality childcare is a key barrier preventing them from increasing their working hours.

Here's hoping that there is a sequel to Borgen in which Birgitte decides to highlight the plight of ordinary working mothers and the role that universal childcare plays in enabling them to work: and that someone makes David Cameron watch the box-set.