Nearly half a century after Ford Dagenham women sewing machinists struck for equal pay, a new survey shows women are still being penalised in the workplace - for having children.

Equal pay for equal work is enshrined in law thanks to the bravery of those strikers, yet a cavernous gender pay gap remains. But now it is the demands of childcare -- rather than sexist bosses -- that is the enemy of equality.

A TUC report has shown that fathers earn 21 percent more than other men. Mothers over the age of 33 typically earn 15 per cent less than women without children.

Men usually work longer and harder when they have children. Women, who have children, even full-timers, often do the opposite at work. They become clock-watchers and part-timers, turning down promotions and skipping travel.

Of course, many mothers put their jobs on the back burner by choice. But there are many who would like what men have always had the chance of: a fulfilling career and children. And those who make their jobs a low priority may count the cost in stalled careers and paltry pension pots.

Working mothers are also seen as less reliable and responsible. The TUC report cites international research which says CVs from fathers were more highly rated than identical ones from non-fathers. But CVs from mothers were marked down compared with those from women without children.

Sadly, the bias against working mothers is sometimes rooted in fact. It’s hard to be reliable and responsible at work when bearing the brunt of childcare. That is still largely deemed a mother’s province. A friend who is a top executive always gets the call from her son’s school when he is ill, although her husband is a stay-at-home dad.

Men collude in all this, of course. I have often heard them grumble about extended maternity leave causing disruptions. But the same men seem blissfully happy that their wives take every day of leave they are due because it makes their lives easier.

Women who try to keep up standards wear themselves out, working through lunchtimes to make up for not being able to work late. Then they trudge home to childcare and housework while their child-free colleagues go networking.

Any mother wanting to be taken seriously at work needs a supportive family network, or enough money to afford professional childcare. And they need backup in case their arrangements collapse. And maybe, as one mother told me she had, 'back-up for the back-up'.

The TUC’s answer to all this unfairness is predictable. It calls for more flexible working, jobs with shorter hours and fathers to be given independent paid childcare leave. Oh, and it wants more people to join a union to lobby for better deals.

Companies can and should do more to help working parents. And it pays to be nice. Happy employees are more loyal and productive. But employers do not have a magic wand. They cannot be sole agents for change.

Whatever was offered, many men won’t willingly request flexible working and time off, for fear of hurting their careers. No, change has also to come from the grassroots - like it did in Dagenham. Women wanting more money need to step up to the plate. They need to make more demands on their partners. They need to take work as seriously as men, and ask for pay rises.

Once I opened an envelope at work to be told I had been given a derisory pay rise which didn’t reflect my far heavier workload. Furious, I marched into the boss’s office waving the offending letter and telling him it was an insult. He smiled, brandished a pen and added a nought to the figure. Women need to know their worth - and have the courage to ask for it.

And women and men should bring their children up knowing that housework and childcare isn’t something that only women do. That girls can enter higher paid professions and become scientists and engineers and astronauts.

In the last 100 years women have fought for the right to work as equals. At the start of the last century the civil service and schools had a 'marriage bar' forcing women to resign on marriage - after all they now had a man to support them. After the First World War, women who were encouraged to work while men were fighting were then vilified for taking jobs it was thought should have gone to ex-servicemen. Women could not get unemployment pay if they refused a job in domestic service.

Unions opposed women working in new industries, frightened that the influx of cheap labour would lower wages. Even in the swinging sixties, those skilled Dagenham women workers earned less than men who swept the factory floor. We’ve come a long way. But we have a long, long, way to go.

Lynne Bateson is a freelance writer and journalist. She was a national newspaper financial editor and consumer columnist.