When gender pay gap reporting was made mandatory in the U.K., in 2017, campaigners were understandably upbeat. Government statistics had consistently shown companies pay women less than men—now it was time to expose the worst offenders.

Two years on, the celebrations are slightly more muted. While companies with the biggest pay gaps have been criticized in the press, the deluge of information and repetitive nature of the stories has lessened the impact of the numbers somewhat.

Anyone hoping to discover a simple figure to ­demonstrate discrimination at an institution might feel ­disappointed, especially when that ­institution is a law firm. The mean and median pay gap are provided for staff as well as for partners. The combined staff and partner averages are ­offered too. The bonus pay gap is also disclosed, as is a breakdown of the numbers by each quartile of earners. Which one do you choose? Slaughter and May’s 2019 announcement spanned 10 pages.

This data dump can prove confusing. Freshfields Bruckhaus Deringer, for example, had among the smallest pay gaps for its staff and partnership alike. But its overall combined figure was one of the worst. This strange outcome can be explained by the fact that the firm has so many more male partners than female. Although its female partners may do fairly well in comparison to their male counterparts, they hardly move the needle when their remuneration is combined with all the women working in the firm. The large cohort of male partners, on the other hand, has a major influence on the average figure for all men at the firm.

The disclosures don’t necessarily shine a light on ­injustice. Because the reporting requirements do not ­provide a like-for-like comparison for jobs there is no way of knowing if a male secretary and a female ­secretary receive the same amount, nor whether a fourth-year female associate receives the same as a male fourth-year. It’s easy for firms to argue that their numbers have been skewed by having more women on lower salaries, such as in secretarial roles.

At the same time, firms can narrow their pay gap by outsourcing lower-paid functions more often performed by women, such as secretaries. Conversely, firms that purposefully hire a large number of junior female lawyers will also be penalized as they see a rise in their pay gap.

There may be other ways to obfuscate the ­numbers. Midtier U.K. firm Weightmans, for example, did not ­include equity partners in its partner gender pay gap ­calculation. Some female partners privately question whether other numbers have been affected with similar ­reporting tricks.

And because almost all the firms are similarly poor—the vast majority of the top 50 firms have a combined pay gap number (for all staff and partners) between 50 and 70 percent—a cynic might say they just need to improve very slightly year-over-year and try not to end up at the bottom of the table.

Many firms seem to have already taken that approach. Compared with last year, the average gender pay gap fell by less than 0.5 percent for the top 50 U.K. firms combined. But for a typical large U.K. firm, a 0.5 percent improvement each year would mean it would take 100 years to reach parity.

That does not mean firms have dodged all criticism. Macfarlanes was outed as perhaps the worst of all the top U.K. firms this year, but the criticism it attracted has arguably drawn fire away from other firms, almost all of which deserved it. A victory for campaigners, perhaps, but the wider problem remains.

Email: phodkinson@alm.com