The books industry may be dominated by women, but men are reaping the rewards, as the UK’s largest publishers reveal a “stark” divide in pay.

Figures reported to the government equalities office from Penguin Random House, Hachette UK and HarperCollins reveal that while women make up almost two thirds of the workforce, on average men are paid more.

The biggest disparity was seen at Hachette UK, where the median gender pay gap was 24.71%, and the mean gender pay gap was 29.69%. Hachette attributed the imbalance to issues including the higher number of men in senior roles; the higher proportion of women in lower pay brackets; and the higher number of women working flexibly and part time. When employees from the wider entity of the Hachette UK Group were taken into account – which includes warehouse staff from Hachette Distribution and LBS as well as other publishing imprints – the difference is less glaring, with women paid 14.18% less using the mean and 1.32% more using the median.

The UK’s largest publisher, Penguin Random House (PRH), reported that women were paid 1.6% more than men when considering the median, which compares mid points of the pay distribution. But using the mean – which totals the hourly rates of pay for men and women and divides by the number of male and female employees – the pattern was reversed, with men earning 11.3% more on average than women. According to PRH, this gap was partly attributable to “an increased proportion of men in more senior and higher paid roles in comparison to our overall gender split”, and partly down to a high proportion of male contractors used during the reporting period.

At HarperCollins, the median pay gap was 10.41%, and the mean was 16.06% – a situation that company attributed to “an increased proportion of men in the top quartile where we have more highly paid roles”.

Figures from the book industry are comfortably better than national averages, which stand at 18.4% for median earnings and 17.4% for mean earnings.

All three companies employ more women than men, with a split of 58% at PRH, 66% at Hachette and 64.5% at HarperCollins. But the balance was reversed at board level, with 44% of the board at PRH female, 33% at Hachette and the executive committee at HarperCollins made up of a male CEO in addition to eight men and eight women.

Hachette UK’s chief executive, David Shelley, told the Guardian that he was “saddened” by the company’s results, “but unfortunately not surprised in many ways, as I am really aware that there are a disproportionate number of men in the top quartile”.

“It is an historic imbalance, and we are taking huge steps to correct it,” he said, pointing to initiatives including unconscious bias training, which was rolled out last year, improvements to parental leave, blind recruitment, and a “diverse future leaders” mentorship programme in which board members mentor a member of staff who aspires to board membership and feels underrepresented on the current line-up.

Staff, said Shelley, had reacted with “shock, sadness [and] frustration” to the report, “but also with a great amount of will to change things and create something different”. The company has set the target of 66% of its top pay quartile being female by 2020, to match its overall gender balance, with 50% of its board to be female.

“The numbers are stark,” he said, “but there is an extraordinary group of people at Hachette dedicated to changing the story for us, and I feel very dedicated to working with them in the years to come to make Hachette a gold standard employer in terms of representing all people at all levels of the business.”

Penguin Random House said it hoped to “work towards a more balanced gender representation in the layer below senior leadership” and introduce initiatives including transparent pay banding as it tackled its gender pay gap.

“We recognise there is more we can do to better support women working across our organisation, to level the playing field and ensure a truly gender-neutral working environment,” it said in its report.

HarperCollins said in its report that “while it is positive that our gender pay gap is lower than the UK average we know there is more we can do”, citing planned initiatives and programmes already in place “to encourage both the retention of senior women and the recruitment and progression of more women into senior roles”.