Clifford Chance (CC), Ashurst and Eversheds are among a band of ten firms to have signed up to a major new initiative to boost women partner numbers across professional services firms in the UK.

A 10-week research project conducted with the law firms, alongside seven major accountancy firms, found that inconsistent application of diversity initiatives was the biggest hindrance to increased numbers of female partners at professional services firms.

The project, which was led by the 30% Club – a voluntary organisation of key business people committed to raising the numbers of women on company boards – aimed to discover why, despite various efforts to increase the number of senior-level women to date, progress in the professional services sphere remains limited.

Following research with the 10 law firms – which also include Allen & Overy (A&O), CMS Cameron McKenna, Freshfields Bruckhaus Deringer, Linklaters, Reed Smith, Herbert Smith Freehills and Slaughter and May – the 30% Club has suggested a number of proposals aimed at counteracting this, including enforcing greater accountability for progress among all partners and introducing a shift from a diversity strategy focussed on women to a "talent" strategy, with particular focus on sponsorship. The group also suggests firms should review their systems for appraisals, work allocation and promotion.

Research by the 30% Club indicates that at the current rate of promotion to reach 30% female partners by 2020 would mean six out of 10 new partners will have to be women, and for 20% it means three out of 10.

Having interviewed senior management and HR, as well as conducted an online survey of over 700 fee-earners at the firms, the 30% Club found neither attrition nor lack of attention to the issue are the biggest problems affecting the number of women partners. Rather the group believes that inconsistent commitment to diversity at all levels in firms, as well as the difference between men and women's perception of partnership were the root cause.

Ashurst senior partner Charlie Geffen said: "There is still a huge journey to travel. If you think about it almost all businesses today were designed by men so there's a whole culture that needs to change and that's incredibly difficult.

"The more pressure we put on ourselves and the more peer pressure there is to make these changes the better. We announced a target of 25% of senior management positions to be held by women and if you have more women involved you get different decisions and over time the number of female partners generally should also increase in line with this."

A&O senior partner David Morley added: "It is absolutely critical to the future success of our business that we attract and retain the best people, including lawyers who could be our future partners. Losing talented associates shrinks the potential pool from which those partners will emerge. Having contributed to the 30% Club initiative the onus must now be on us to take the ideas back to our firms to decide what will make the greatest impact. The success of PRIME demonstrates the progress this sort of profession-wide collaboration can make."

Findings and ideas were presented at an event hosted by Linklaters last night (12 December) to an audience of over 150 people, including senior leadership and key stakeholders from participating firms, the 30% Club Chairmen, the Law Society and the Institute of Chartered Accountants in England and Wales (ICAEW).

Firms recently setting targets to improve gender balance in the partnership include Hogan Lovells, which in October outlined aims for a 25% female partnership by 2017 and 30% by 2022.