Mention flexible working and people have certain ideas. A rosy picture of conference calls in pyjamas, lunchtime swims, maybe a desk under a tree in the back garden. Gliding through our inbox in peace at 8am and logging off by 4pm. These are all ideas had by people who have never actually done flexible working, of course, but we can’t let the dream die.

The lack of flexible working opportunities – including variable start and finish times, working from home, or the option to work fewer days – has been identified as the main driver of the enduring pay difference between men and women.

It makes sense. For mothers returning to work from maternity leave, those few hours of leeway can be the difference between career confidence and a career abandoned. Flexibility gives part-time workers extra opportunity, and makes the daily grind bearable for staff whose dreams don’t begin and end with their LinkedIn page.

But flexible isn’t always easy. Without the supple attitudes and nimble management to match, trying to make a formerly 9-to-5 job work on new terms can be like trying to do a yogic backbend without warming up first.

First there is the risk of resentment from colleagues back in the office, who are convinced you really are writing that report from a spa or leaving early to go shopping. There is also the worry you will become the phantom colleague, just a disembodied name in people’s inboxes who nobody ever remembers to invite to the party.

One of the biggest pitfalls is that many managers don’t have the skills to manage performance effectively for flexible workers. They need to measure performance on the outcomes of the work, not on the time spent or how much they see them around the office. It’s all too easy to lapse into an ‘out of sight, out of mind’ approach.

While we might know we’re more productive in the quiet calm of our own homes, the fear of being considered a slacker can turn into digital presenteeism – replying to emails long after you should have logged off, as a way of waving a flag that says “Here I am! Still doing my job!” And it’s all too easy for managers to take advantage.

For those companies that can make flexi-working work, they have a more productive team, happier employees and a really energetic business. But for it to have a positive impact on a business everyone needs to be on board, from the top down. You have to be uber organised otherwise it will fail, with meetings going unattended, projects being mishandled or creativity being stifled because of a lack of connection between the teams.

Technology needs to be flexible enough to cope with the load, too. Skype needs to work, files need to be accessible, the IT team needs to be easily contactable. People need to learn to use email in a way that’s personable, not just “Action this by EOP, regards” perfunctory.

And, of course, attitudes need to change along with legislation. The bums on seats brigade needs to see flexible working as a real option for everyone, not the preserve of working mothers. But there’s a way to go; researchers in Australia have found that men were twice as likely as women to have their requests for flexible working rejected, while those working flexibly were less likely than women to feel secure in their jobs and confident about future promotion.

Flexible working is an important part of closing the gender pay gap, but it’s not the only measure. There need to regulations that will require large companies to report on how they pay men and women, which is going to put a real spotlight on the gender pay gap. Transparency is the most powerful driver of change.