Gender diversity in the workplace within the most senior positions has increased significantly over the past five years, new research suggests.

A study by credit rating agency Experian has revealed that between 2007 and 2012, the number of women in director positions at UK firms has risen dramatically, from just over 993,000 five years ago to more than 1.23 million today – an increase of 24 per cent.

In comparison, the number of male directors has risen by 15 per cent over the same period, from 4.26 million in 2007 to 4.98 million in 2012.

“Much of the existing available data about female directors focuses on FTSE companies,” said Max Firth, UK managing director for Experian’s Business Information Services division.

“We’ve used our extensive database, comprising nearly three million companies and 100 industry sectors, to show a more in-depth picture of the number of female directors across the UK.”

Experian’s figures show that small companies (those with between three and ten employees) are more likely than large companies (250 or more employees) to have female directors.

However, this gap is narrowing, with the data revealing that, in 2007, 48 per cent of small companies had at least one female director compared to 33 per cent of large companies, rising to 50 per cent of small companies and 40 per cent of large companies as of 2012.

Start-up businesses have also been important in bolstering the number of female directors employed over the period, with a third of the 1.4 million businesses that started up since 2007 having one or more female directors.

“Smaller companies are clearly the driving force for female directors, but our research shows that larger companies’ efforts to increase the number of female directors have made a significant difference over the past five years,” said Mr Firth.

“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.”