Rule one of being a working mum is never to use your children as an excuse. The house may have burnt down, the bus may have run you over - but you are never, ever late because the nanny didn’t turn up and you don’t have childcare. There may be the odd other mother in the office to whom you can confess the nightmare of your prework morning; who understands how, with your pulse rate heading to palpitation levels, you heaved your kids into their clothes, made the packed lunches with one hand while speed dialling your mother, sister, cleaner, daughter’s best friend’s mum until someone was persuaded to take them to school but, generally, the rule stands.

This ethos is so much a part of me that I’ve been taken aback over the past few weeks when men who work for me have turned down assignments by saying, unapologetically, “Sorry, no, I can’t do that. I’ve got to look after my kids that morning.”

The first time it happened I was appalled and harrumphed around my office going, “If I can sort out someone to cover the kids while I’m at work, why the hell can’t they?” My mother, who worked, drummed into me that if you are a mum and you work it’s up to you to sort the logistics - and the boss should never have to hear about it (probably the result of years of first-wave feminism conditioning about being able to do a job as well as any man).

Don’t get me wrong. I’m not whingeing. Despite last week’s research about how working mothers do a “double workload” (according to a new 20-year study by the Economic and Social Research Council, we work an extra 15 days a year when you add in home responsibilities), I don’t feel sorry for myself. I know I do a double shift. And yes, it’s knackering and there are juggling moments when I drop the balls, and sometimes I am stalked by guilt. But I chose it.

I love my family and I love my job - my life is enviably full and fulfilling. And this government - and my forward-looking employer - has bent over backwards to try to make it work for me. All mothers now have the right to ask for flexible working (I work from home one day a week). I work hard but I have a good deal; the structures are in place to make it manageable. And I have a brilliantly supportive husband - but more of him later.

The ones I feel sorry for are my male peers. I am 36 and among my generation there is much more true equality when it comes to parenting (as there is in other aspects of our relationships). Most dads I know willingly do their share. From the moment the baby is born (usually with their help) they change nappies, do night feeds and co-parent. They are equal partners in the child-rearing enterprise. (Would you dare to tell a modern woman the children are entirely her domain? Quite.)

But while mothers can now have up to a year off with their job legally being held open for them, (with up to six months paid), the doting dads go straight back to the office. Some dare to take up their two weeks’ paternity leave (enduring the ribbing of older colleagues who think they are soft - just think of the stick David Miliband and David Cameron got). Others are terrified they will be seen as uncommitted, or not promotion material and are squeezed between the traditional role of dad-as-provider in a macho work culture and their desire to be really intimate with their offspring.

This angst is real; I’ve lost count of the number of chats I’ve had with quietly distraught fathers who hardly see their kids during the week (British dads work the longest hours in Europe).

Pictures of the adored sprog are shown off secretly, samizdat style, on their computers or on Facebook. Many tell me how jealous they are that as a woman I get to have my cake and eat it; do the big job and see my kids (unlike many male friends, I have pictures of my girls all over my office).

As I head off for my day at home, I feel for them at the office coalface, required to toil away long after their kids are in bed. In an age of equality where dads are expected to shoulder as much of the home burden as mums, it feels unfair.

Inevitably there is a backlash. Spearheading this are the self-employed, or flexi-working fathers who can wear their caring-daddy status with pride. The types who proudly tell you they can’t work as they are doing the kids. They are the male equivalent of the stay-at-home-mum brigade.

In America, always a little ahead of us when it comes to social trends, the daddy wars are in full swing. Last month’s US Men’s Vogue featured an impassioned polemic from Pulitzer prize-winning journalist Charlie LeDuff about how he had given up the rat race to “stay home and raise his daughter”.

A growing group of men there are as passionate about why fathers should be as fully involved in raising their children as any mother and they are over here, too - the number of dads at the toddler singing groups I go to is rising weekly.

When I first started going, five years ago, they were rare. In my urban neighbourhood, full of non-office-based creative fathers, you see almost as many dads at the school gates as mothers.

My husband is among them. The reason I can do a demanding office job is because he is employed by a website and can work flexibly.

In fact his web 2.0 bosses are so family-friendly that he picks our daughter up from school every day and does five days’ work in four days so that, one day a week, he looks after our two-year-old. When the nanny doesn’t show, he’s the one who covers.

There has been much talk in the past week of a new generation taking up the reins of power (Nick Clegg, 40, poised to be leader of the Liberal Democrats, Cameron, 41, running the Tories).

This generation’s defining characteristic is its belief in equality between races, sexes and so on. The first generation of working mothers fought their corner pretty well; their legacy to us, their daughters, is that our lives are tough and tiring but these days the law and employers treat us pretty well.

The next revolution in the workplace - already being spearheaded by fathers such as Cameron, and part of his appeal - is about men and their right to a different kind of family life: the daddy wars are upon us.

India Knight is away

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