By Domini Pettifar, joint managing director, dnx marketing

Do British businesswomen need more swagger? It is a question I raise, in all seriousness, as the subject of women as corporate directors has become a hot topic well beyond the boardroom. Prime Minister David Cameron has said he would consider instituting quotas to increase the participation of women on boards–a year after Lord Mervyn Davies issued a scathing report calling for companies on the FTSE 100 to increase the proportion of their female directors to 25% by 2015, from about 15% today.

These efforts are well-intentioned but fraught. Few would dispute that a boardroom that reflects the workforce is anything but good for business (and the general well being-of society). But no corporation wants to be told how to manage its business by government, and women don’t want to secure seats on boards to simply to satisfy legislation.  They will wonder if it’s mediocracy or meritocracy.

More importantly, these measures do nothing to address the root cause of the abysmally low numbers of women on U.K. corporate boards–which brings me back to my original question: Do women in the U.K. need to be more assertive, more like their U.S. counterparts?Consider Augmentum Consulting’s figure that women make up just 9% of the boards of FTSE 250 companies; if this wasn’t a poor enough result in itself, this 9% is made up of many female U.S. nationals, such as the highly talented Angela Ahrendts of Burberry  and Logica’s Jan Babiak. (The number of American women leading U.K.-based companies is also notable: Besides Burberry’s Ahrendts, Pearson’s CEO Marjorie Scardino and Anglo American CEO Cynthia Carroll also hail from the U.S.)

What gives? A new piece of British research by the Institute of Leadership & Management concluded that men were 30% more confident than women in the workplace.  If we as women don’t believe in our own ability to reach the boardroom–and stay there–what hope do we have that others will believe in us?

I believe there is a real lack of self-belief endemic in the female working population of the U.K. and one that is at complete odds with our U.S. counterparts.

Part of the problem stems from a society that, in my experience, doesn’t place high expectations on most girls’ career prospects. As a convent-educated female of a very traditional Army Officer father my professional aspirations were never discussed.  Whilst my brother went on to gain a good degree from Oxford I limited my higher education preferring to get into full-time employment as quickly as possible.

Marketing seemed to present more rapid career advancement to women over many other professions and during my early career I was lucky enough to have two senior bosses who not only gave me ample opportunity to step up to the mark and gain new skills and experience, but importantly were happy for me to do so.

At the age of 28 I conducted a management buy-out of the agency that had employed me for the previous two years. Did I have the experience to do so?  I most certainly did not!  Had  I gained the confidence that I should at least give it a really good shot? I certainly had.

What we really need is the realization and appreciation that if the U.K. is to emulate the U.S. (not the paragon of equality–female board representation at the 200 largest companies by revenue  is about 20%–but streets ahead of the U.K.) then the creation of a level playing field is essential.  Career expectations for women, along with the education and behavioral agenda has to change.  Imbuing confidence and self-belief is not a short term fix; for any woman it has to start in the cradle and continue to  grow and build  throughout her whole working life.  Nothing less will do the job.

Domini Pettifar is joint managing director, dnx marketing, a U.K.-based agency that specializes in busines-to-business marketing and communications.