Behind all the slogans and initiatives around gender equality are vast stores of equity partner profits, concentrated in the hands of men. 

Ask any law firm leader and they'll tell you that gender parity is high on the agenda. Targets set, initiatives launched, PR strategies carefully devised. But much of the progress we've seen lately evades one of the things that matters most: the number of women with a share in the equity. 

Despite this modern era of transparency in which firms have started to disclose once-sensitive data on their pay gaps among women and, to a lesser extent, ethnic minorities, many still keep schtum on the equity. Most of the U.K.'s top 10 firms refused to disclose the gender divide at equity level when asked by Legal Week.

That included four of the five Magic Circle firms – Clifford Chance, Freshfields Bruckhaus Deringer, Allen & Overy and Linklaters. Slaughter and May, on the other hand, revealed that about a quarter (25%) of its partnership was female and equity. 

Other major U.K. firms to duck the question include Herbert Smith Freehills and Eversheds Sutherland. Replies were invariably along the lines of: "This is not something we disclose." Via email, one simply responded: "N/A."

The effect is that the gender divide at equity level is overlooked as a yardstick for measuring gender equality in law. It's a clever sleight of hand. This way, any ostensible shift by a law firm toward parity, however negligible, gets plaudits while the underlying issue goes unresolved. 

Common are the stories around 'creating gender balance on teams', 'promoting diversity among barristers we instruct', 'topping associate gender rankings' and 'launching outreach programmes for female students'. And many of these are worthwhile efforts.

But when the equity partnership – the beating heart of any law firm – is sheltered from censure, how seriously can we take these grand proclamations and initiatives on gender diversity?

To get a sense of the scale of the problem, a Thomson Reuters study in June – Transforming Women's Leadership in Law – found that 22% of equity partners at law firms were women, representing "a significant drop-off compared to the 61% of trainees who are women". 

A person at Acritas – the company that conducted the research – said the 22% figure is an aggregate of data obtained from about 2,000 partners at a variety of law firms, rather than from the firms themselves. Acritas was unable to provide a breakdown of individual firm data. 

Simply put, this figure can't be used to hold any one law firm to account.

Many firms have started disclosing their overall partner gender pay gap, albeit amid parliamentary pressure. And not all top firms have shirked questions about gender balance at equity.

CMS has reported a 31% female partnership, of whom nearly all (95%) are equity partners, for example. At Gowling WLG, 84 of 148 female partners have a share in the equity, and at DLA Piper all 254 global female partners are equity. Not quite 50% of Ashurst's 102 U.K. female partners are equity, while Hogan Lovells (63% of its female partnership) outstripped Pinsent Masons (18%) and Clyde & Co (17%).

Though some of these numbers are alarmingly low, it seems almost perverse to criticise these more transparent firms while others remain so obstinately private.

For those that hide the numbers, gender inequality at the top is free to quietly persist. And when questioned, stock responses are common.

For example, where a firm operates a lockstep pay model, the popular retort is that it will take time for things to change. "Women will come through the system, but that could take a number of years because we're lockstep," said one person at a Magic Circle firm, a sentiment echoed by others.

Being at the mercy of this inch-at-a-time model accords firms a go-to platitude on which to rest their laurels. Meanwhile, they can continue to peddle out pay gap numbers on the salaried and fixed-share partnership, which do little to shed light on the situation among equity players and may in fact have a contradictory effect, according to one senior female partner at an international firm.

"Law firms posting glowing pay gap figures at partner level but not in the equity is a nonsense," she says. "You throw in the equity figure and you can watch neat little single-digit numbers balloon to double-digit pay gaps."

Also calling for transparency at equity level, another female partner at a large U.K. firm asks whether "salaried partners" are "even partners at all", adding: "It's all about the equity… We need numbers on the real partners."

For women just entering the profession, the hope of equality still exists. Not least because they are lured by law firms parading diversity initiatives whose outcomes are visible only at the more junior end of the career ladder. Yet as long as the gender divide at the top remains a clandestine affair, there will persist a gap not only in pay, but also in how much one can really know about their anticipated career path. 

Most firms seem to acknowledge that change is needed to bring about a better gender balance. But until we see complete transparency at equity level, law firms raving about their diversity credentials at best smacks of hypocrisy, and at worst, of a cover-up.