The government is calling for executive headhunters to sign up to a code to prove their commitment to placing more women appointments on FTSE 350 boards.
Business secretary Vince Cable said: “Executive search firms are crucial to achieving gender diversity in both executive and non-executive roles. Recruiters can best show their commitment to this work by embracing this new enhanced code.
"Now that all FTSE 100 boards have at least one woman serving on them, and all key stakeholders have embraced the gender diversity agenda, we are confident that with sustained and continued action, we will meet the target of 25 percent women on FTSE 100 boards by 2015."
The first voluntary code of conduct, drawn up in response to Lord Davies report on the lack of women on boards in 2011, drummed up support from 70 head-hunting firms for companies on the London stock exchange.
This new voluntary regulation comes in response to the independent Sweeney review of Women in Boards in February this year. It will give recognition to firms who have recruited the most women to FTSE 350 boards and those working to lay foundations for higher female representation in the FTSE board directors of the future.
Under new provisions, search firms will provide evidence to Lord Davies' steering group that they have supported the appointment of at least four women to FTSE 100/250 per year.
Further, they must prove they have achieved at least 33 percent female appointments across all their FTSE 100/250 work in a given year.
“I am looking forward to finding out which firms have passed the higher standard set by industry,” Cable said.
The last all-male board in mining group Glencore Xstrate appointed its first female executive this month, Patrice Merrin.
The absence of women in the technology industry has been scrutinised following Facebook's disclosure of its workforce's gender and ethnicity make-up.