Progress on appointing more women on to company boards has stalled, suggesting that firms have become complacent in tackling the issue, according to a new report.
The annual Cranfield Female FTSE board study showed that in the six months from last March the pace of change was "extremely encouraging", with 44% of new appointments going to women, and 36% in companies in the FTSE 250.
But the levels were short-lived, dropping to 26% and 29% in the past six months, showing a "considerable gap" from the recommendation of having 25% of women on boards by 2015, made by a Government-commissioned review led by Lord Davies of Abersoch.
The Cranfield International Centre for Women Leaders said there was a 33% gap between the current rate and the recommended level.
There are 194 female-held directorships, involving 169 women, in 93 of the FTSE 100 boardrooms, equivalent to 17.3% of the total, compared with 15% a year ago, said the report, leaving seven with all-male boards.
Dr Ruth Sealy from Cranfield School of Management, who co-authored the report, said: "Lord Davies' target for FTSE 100 companies is still in sight but only if the rate of new appointments going to women regains momentum promptly.
"Only a quarter (25%) of FTSE 100 companies have already achieved the target and the drop in the last six months is worrying. It is disappointing to see that women from outside the 'corporate mainstream', including entrepreneurs, academics and civil servants are still not being considered for FTSE board positions."
TUC General Secretary Frances O'Grady said: "While we welcome recent cross-party efforts to alter boardroom culture, this has not led to meaningful change. These figures make for depressing reading. The only way we will end the old boys' network is if the Government introduces compulsory quotas for the composition of boards, as recommended by the European Commission."
Minister for Women and Equalities Maria Miller said: " We are making good progress: two thirds of women are in work, the gender pay gap is closing and both Lord Davies' and Cranfield's reports indicate that we are heading in the right direction when it comes to women's representation at senior levels.
"But there is much more work to do. The priority now is to maintain that momentum, not only within listed companies but across the economy as a whole."