The study of over 2.7 million businesses found that although small companies (3-10 employees) are still more likely than large companies (250+ employees) to have female directors, the gap between the two is narrowing.
The study claims that in 2007, 48% of small companies had at least one female director compared to 33% of large companies and in 2012, half of small companies had female directors compared to 40% of large companies.
Although the increase in female directors is positive news for women looking to break the 'glass ceiling', the study found little change over the last five years in the types of profession dominated by males.
Over the five-year period to 2012 there were less all-female boards in 2012 in some typically male-dominated professions such as plumbing, installation of electricity and software publishing.
Max Firth, UK managing director for Experian's business information services division, said: "Smaller companies are clearly the driving force for female directors, but the study shows that larger companies' efforts to increase the number of female directors has made a significant difference over the past five years.
"And let's not forget the contribution made by female entrepreneurs, with many starting up their own companies to manage work/life balance and fit with family commitments, without whom the number of female directors would be considerably lower."
Firth added: "But when it comes to different industry sectors, the data shows that the picture is fairly static."
