While there has been a lot of talk about making work more flexible for women returning from maternity leave, a new University of Sydney study has found the talk has not filtered through to the coal face.

The research, to be published in the UK journal Employee Relations, has found that fewer than one in five employees had a detailed knowledge of flexible work policies.

Ms Hooper, a human resources director for a commercial real estate firm with two young children, said she recently secured a challenging part-time role as a senior executive, but it was difficult finding a senior position that offered flexibility.

"In the six months that I was searching for a new position, there were no part-time roles that were advertised or that I was able to apply for.

"I presented myself as a candidate who could work for three or four days. Many were not open to the idea and just wanted a traditional full-time resource. But fortunately, this company was willing to consider a flexible working arrangement."

Rae Cooper, an associate professor in Work and Organisational Studies at the University of Sydney Business School, said the study, based on long interviews with 44 employees and 22 line managers, had identified a significant gap between what should happen in theory and day-to-day practice in workplaces.

"In the last 10 years, we have had more policy development around flexible work, both at the national and the organisational level, to allow for a more meaningful combination of work and family life," she said.

"If you don't allow women to do that in a meaningful way, you lack a capacity for women to build a career and have children.

"Unless you make it possible for women to make their career trajectory work, you are going to have women working at a lower level or dropping out. Mothers will often choose to work at a lower level over longer hours."

Professor Cooper, who co-authored the study with university colleague Professor Marian Baird, said less than 20 per cent of employees had a good working knowledge of policies designed to improve workplace flexibility.

Because many managers were not versed in policies to improve flexibility, they were not being implemented.

"Line manager support is critical for making flexible arrangements acceptable, encouraged and manageable for working parents," Professor Cooper said.

"It is in the interest of senior managers to educate people about these policies.

"We have formal policies – but informal negotiations about them because people often don't read them."

Professor Cooper said women were more likely to go to family and friends and mothers groups for advice instead of approaching their human resources department, a union or a specialist advice line.

When it came to negotiating more flexible working arrangements, they were more likely to say they wanted reduced hours, but rarely had a conversation about how their performance would be measured or how they would deal with work they could not complete within those shorter hours. This often led to women doing many hours of unpaid work.

The new study, funded by the Australian Research Council, comes as national figures show the gender pay gap in Australia has increased from 17.8 per cent to 18.8 per cent since 1985.

But Diversity Council Australia chief executive officer Lisa Annese said Australian data published by the Workplace Gender Equality Agency said many employers are still failing to maximise their female talent.

"There's no quick fix here – employers need to do the hard yards. Strategies like actively sponsoring women and other diverse talent into leadership positions, addressing bias at every level, adopting broader definitions of what leadership looks like, and public accountability via reporting on measurable outcomes will actually deliver results," Ms Annese said.

"It is concerning that underemployment has increased from 5.3 per cent to 11.2 per cent in the last 30 years.

"Once you have been sidelined off a full-time career path, it is hard to get the employment level you want."

Ms Annese said women often had to settle for lower wages because they were seen as aggressive when making a case for an increase.

"Women are often told they should speak up more, but when they do, they are often punished for it," she said.

"Some of it is downright discrimination and some of it is not conscious.

"The fact that the gender pay gap is increasing shows it is insidious."