Bird & Bird has emerged as the UK top 20 law firm with the largest percentage of female partners, with Hogan Lovells topping the rankings within the top 10.

Legal Week research into female representation at partner level across the 50 largest UK law firms by revenue found a trio of regional firms emerging as the most female friendly partnerships, with Berrymans Lace Mawer overall having the largest proportion of women partners in the top 50, with almost 37% of its partnership female – virtually double the average. It was followed by Shoosmiths and Irwin Mitchell.

Bird & Bird is the highest placed firm within the top 20, with women making up just under 23% of its partnership as at 1 May 2011, closely followed by Berwin Leighton Paisner and Pinsent Masons.

Transatlantic firm Hogan Lovells is the highest ranked top 10 firm, with women making up just under 21% of its partnership, against an average across the whole of the top 50 of 18.6%.

In total there were 2,022 female partners at top 50 firms as a whole on 1 May, out of a total partner count of 10,865.

The magic circle fell significantly below the top 50 average, with each having no more than 15% of women in their respective partnerships, with the exception of Slaughter and May, which has 18% female partners.

Freshfields Bruckhaus Deringer counted just 12% female partners, while Ince & Co was the least representative top 50 firm, with just 11.5% female partners.

Bird & Bird chief executive David Kerr commented: "Over many years we've been trying to make the partnership really attractive to our female assistants; after all, slightly more than 50% of the intake into the profession is female, so it would seem a bit strange if we were not trying to adapt things to retain this figure. I've always been a fan of having female partners in key leadership and management roles, too."

Berrymans national senior partner Terry Renouf (pictured) said: "I do think technology has made an impact somewhat, allowing people to work that much more easily away from the office, which of course makes a difference to family life. However, I also think we have an attitude to flexible working as a perfectly acceptable lifestyle choice."

Legal Week's research comes after numerous City firms have been taking steps to boost the number of women in their partnerships in recent years, with women making up around 25% of new partner promotions across the top 50 this year and Bird & Bird, and Trowers & Hamlins making entirely female promotion rounds.

Hogan Lovells diversity co-chair Ruth Grant said: "We have a very inclusive culture and working environment, which makes us attractive to women, and also a very balanced practice, which may attract more women to stay with us compared with firms that are purely transaction -orientated.

"We have a women's network and offer internal mentoring for our female lawyers and we are actively focusing at the moment on what we might do to grow our female partner numbers by looking at how we can better support our female associates that are on the partnership track."

The research does not include Withers, DWF or McGrigors, which are yet to announce their partner promotions for this year.