Women in board positions have to be extra careful and confident in the valuethey add, according to a study of FTSE 100 female board directors.

Successful female board members are adept at challenging but do so in a non-threatening way, are not as egocentric as male board members and focus on their organisation's goals rather than their own agenda.

They take their role as non-executive director very seriously and take time to choose the right board to join. Usually, they have worked so hard to get to the board and are so well-qualified and prepared that, as one female board director said, "they raise the bar for everyone".

The research, conducted by boardroom consultancy firm IDDAS, comprised in-depth interviews with 24 high-flying women, a fifth of all female board directors in the FTSE 100.

Unveiling the study to board directors at the Ritz this morning, project director Hilary Sears said: "Female board directors are used to being in the minority but it did make a difference when there was a second woman on the board. When there is a sole woman she is often seen as a stereotype."

She added that it was important that female board directors did not get "pigeon-holed" as the person who only ever speaks on the soft issues.