Carrie Gracie’s open letter appealing for equal pay has dramatised a fight that has already been going on for the best part of 200 years. Her principled stand cannot be dismissed just because the sums involved are way beyond most people’s wildest dreams. She is very well paid. But her argument is about fairness: she wants the BBC to stick to the law. It must value men and women equally. Nearly 50 years after the equal pay act, it is shocking that it still needs saying.

The BBC’s highly rated – but evidently not highly valued – China editor resigned because managers could not grasp that her case was not about more money, but more equality. Having been promoted to one of the big four international editor jobs on condition that all of them – Jon Sopel in Washington, Jeremy Bowen in Beirut, Katya Adler in Brussels and Carrie Gracie in Beijing – were paid equally, she was appalled when the figures for top earners published last summer included the men but not the women. The discrimination could hardly appear more explicit.

For several months, the BBC flannelled around trying to head off a row without dealing with the substance of Ms Gracie’s complaint. Finally, after fruitless negotiations and a protracted and inconclusive grievance process, she did as she had warned the bosses she would, and resigned. She felt the alternative, to go back to Beijing, would be “colluding” with the BBC’s claim of equal pay – rather than continuing to challenge it.

The BBC claims it has a good record on the gender pay-gap; but this is not about the unfair distribution of higher-paid jobs, it is about treating people doing work of equal value the same. And here the BBC is impaled on a pike it made itself with hundreds of secret individual pay deals that were never supposed to be seen by the female workforce. When some of these were exposed by the publication of top earners’ pay, the management tried to deal with the backlash by a policy of divide and rule, offering some rises to as many as 200 women who believe their pay is unfair.

This response was morally wrong and politically inadequate. It perpetuates structural wage inequality that affects workers at every point on the pay scale, from millions of low earners where the median hourly gender pay gap for full-time work is just short of 10% to the elite of top earners where men earn half as much again as women doing similar work. The BBC is not alone. By this April, all companies employing more than 250 people are due to file a report to the government setting out a breakdown of pay and bonuses by gender. This is not, on the face of it, a very onerous obligation. Yet with a couple of month still to go, only 532 employers, 6% of those obliged to make the return, have actually done so. Some of those have rewritten the data on one or more occasion. There is a statistically improbable proportion of employers claiming no earnings gap at all.

Clearly there is nothing unusual about pay secrecy. But a fair society depends on a high degree of transparency and accountability and the BBC is a public service organisation with a particular obligation to stick to the letter of the law. Yet this is also a fight for every woman. Ms Gracie’s brave and principled stand, of a piece with her record as a journalist, should give heart to anyone, anywhere who suspects she is not getting a fair deal.