Slaughter and May has grown its proportion of female partners to 20%, while the figure dipped marginally at magic circle rival Clifford Chance (CC).

Slaughters' latest figures, dated 31 January 2014, show the number of women in the partnership has marginally increased by 1% to account for 20% of the partnership when compared with statistics for 1 May 2013. The percentage of female trainees has stayed static at 46.6%.

The figures also show the proportion of partners self reporting as being from a minority ethnic group decreased in the nine months leading to February, representing 5.7% of partners in 2014 compared with 7% in the previous year. Minority ethnic representation also fell from 20% to 17.3% for solicitors and from 26% to 19.5% for trainees.

Four out of every 10 partners at the firm were educated at a state school in the UK, with 47.1% going to independent or fee paying school. A further 10% were educated abroad, with 2.9% declining to reveal details of their schooling.

The gap widened among all lawyers at the firm, where the figures show 30% attended state school and 49.7% were privately educated.

Those among the first generation of their family to attend university accounted for 45.7% of partners and 19.8% of solicitors this year.

The firm has also released data covering age, sexual orientation, disability, faith and caring responsibilities.

Similar statistics for CC, dated 30 April this year, show that the year on year percentage for female partners has dipped slightly from 16.3% to 16%. In London women accounted for 19% of partners.

The percentage of female fee earners firmwide has also slightly dropped, from 49.1% to 48.5%. The London office's percentage similarly decreased from 53.6% to 52.9%.

Figures also show that the number of London partners self-reporting as coming from an ethnic minority stayed static at nine, the equivalent of 6.3% of the City partnership.

The firm has additionally released figures dated 31 May 2014 to account for newly promoted partners. According to these figures, the firmwide proportion of female partners across the firm is 16.9%, while in London the figure is 21%.

The figures also show 5.6% of London partners are from an ethnic minority group. In recent years CC set a long-term intention of achieving 30% female representation across its global partnership.

The news comes as CC's lawyers have decreased their pro bono contributions by 5.4% to 52,346 hours during 2013-14. The firm's annual corporate responsibility report values the time invested in pro bono work at £18.1m, down on last year's equivalent of £19.2m. The firm has pledged to increase the proportion of lawyers doing pro bono work from 54% to 60% for 2014-15.

Meanwhile, business services volunteering hours dropped by 7% to 4,153, which the firm has vowed to investigate.

The latest data from magic circle peer Linklaters in 2014 show women made up 17% of its global partnership and 22% of its UK partner numbers, while at Allen & Overy (A&O) global female partner count dipped marginally over the last year, from 16% to 15%. Women accounted for 17% of partners at A&O's London office.

Slaughters' efforts to improve diversity at the firm include a working from home pilot initiative, which is open to 89 associates as well as partners across its key practice groups. Participants have been trialling working from home one day per fortnight.

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