Some two-thirds of Britain's top 100 companies have so far ignored calls to set targets for boosting the number of women they have on their boards, a progress report revealed.
The Government-commissioned Lord Davies review, published in February, recommended that firms listed on the FTSE 100 Index should aim for a minimum of one in four female board members by 2015. But an official progress check by the Cranfield School of Management found just 33 companies have heeded this recommendation.
Elsewhere, the Cranfield report said 21 women have been appointed to board positions out of a possible 93 - representing 22.5% of all new appointments, short of the 33% recommended by former trade minister Lord Davies of Abersoch. In February, Lord Davies called on chairmen to announce their targets for 2013 and 2015 within six months, but only 33 have heeded this recommendation.
The Cranfield report said Lloyds Banking Group and Rolls-Royce stood out for "boldly" aiming to increase their female representation by between 20% and 23%.
There was some progress since the review was published, the Cranfield report said, with the number of women holding FTSE 100 board directorships rising from 12.5% to 14.2%, or 155 out of a total of 1,092 positions.
Ruth Sealy, co-author of the report, said: "The results suggest the recommendations in Lord Davies' review have had beneficial effects in terms of reinforcing good practice, but they also demonstrate an institutional inertia, whereby companies persist in their existing approach to gender diversity on boards.
"It is so important that our top companies set the standard for achieving better representation on their boards."