Andrew Stone works four days a week, teaching history and politics to sixth-formers in south London. Or, to be precise, he gets paid for working four days a week; but what happens on the fifth day is more of a grey area.

He first went part-time when his son was born, and initially his day off was spent with the baby. But now that his son is three, Stone usually drops him at nursery in the morning, then comes home to spend the rest of his supposed day off marking or lesson planning.

It’s hardly most people’s idea of a blissful long weekend, and it’s work for which he effectively isn’t paid. But at least this way work doesn’t bleed into the weekends, as it did when he taught full-time. “I understand that there are other jobs where you don’t see the invisible work that goes on behind the scenes,” Stone says. “But the disparity between reality and perception in teachers’ working lives is so much greater.

“The day before the Easter holidays started, I overheard some people talking about teachers and saying, ‘Oh, they work nine to three, then they go down the pub.’ Well, the previous night I’d been up until midnight marking, and I knew that in my Easter holidays I’d be working practically every day, marking the mock exams of hundreds of students as well as planning for the upcoming term.” For him, going part-time is a way of managing not just the ever-growing mountain of paperwork, but the emotional demands of the job. “It’s the guilt, really. There’s constantly more that you could be doing, that you should be doing, as far as your line manager or your head or Ofsted is concerned. You never seem to reach the end, where you’ve achieved all you feel you should have done.” At least this way Stone feels on top of things, rather than worrying about what he might have missed. For him, reduced hours are no longer a way of balancing work and family life, but of managing work itself.

There are an awful lot of others out there doing the same – last year, the Association of Teachers and Lecturers (now the National Education Union) warned of a rash of staff reducing their hours in silent protest against their workloads – and by no means all are parents. Niamh Sweeney, the ATL’s vice-president, says going part-time as a teacher – a decision she took six years ago, when she was single and had no family responsibilities – kept her in the profession, but also “made me a better teacher”, one no longer drained by spending weekends working.

They’re not all teachers, either. One in 10 Britons is now what the Office for National Statistics classifies as overemployed, meaning they work more hours than they want and would take a pay cut to do less. (They now outnumber the underemployed: people who want more hours and can’t get them.)

The underlying truth is that for too many of us, work simply no longer fits into the official working day. More than 5 million Britons put in regular unpaid overtime, to the tune of an average 7.7 hours a week, according to the TUC, and it’s this hidden work – staying late in the office, logging back on at home in the evening – that often fuels resentment. Once unpaid overtime is counted, one in four Londoners is working more than 48 hours a week, with finance workers and teachers among the professions hardest hit.

Busy is becoming the new normal, with public sector redundancies and private sector cost-cutting leaving those still lucky enough to have jobs doubling up for those squeezed out. No wonder there’s a growing hunger for more time to breathe, even if tight budgets still make that impossible for many; the Chartered Institute of Personnel and Development estimates that more than half the workforce now works flexibly in some way – anything from the occasional day working from home to a three-day week.

But while part-time work remains the path to a more relaxed life for many, it can have a darker side. If it’s functioning as a safety valve, allowing some people to hang on to jobs they love even when the pressure gets too much, that may be a practical solution for individuals. But could it be masking an underlying problem of too few people struggling with too much work, while others don’t have anything like enough?

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The right to request reduced hours was originally introduced by Tony Blair’s government in 2002, to help parents of small children juggle work and family. But since then it’s been gradually extended, and in 2014 it was opened up to anyone who has been with the same company for six months, parents or not (employers can still refuse if it’s detrimental to the business). For some, this quiet revolution has undoubtedly been life-changing.

“Twenty years ago, what I do would have seemed weird,” says Mark Webb from his home desk in Buckinghamshire, where he works three days a week as head of social media for Dixons Carphone. The fourth day is spent in the office, and he then takes every Friday off. But what’s unusual about his working pattern is that it wasn’t originally his idea; it came from his bosses.

Ten years ago, Webb was diagnosed with multiple sclerosis. At first he carried on with his then job as head of media relations as if nothing had changed. But, gradually, it became harder to travel – he needed a stick to walk and a wheelchair for longer distances – and eventually he was called in for a chat with his managers.

“I wondered if I was going to get the guilty cheque. But they said, ‘Look, Mark, you’re not coping – we want to keep you, but we want to help you adapt to a role that will help us and help you.’”

What they proposed was a four-days-a-week role running Dixons’ social media channels, preserving his old level of seniority within the company, but letting him take Fridays off and avoid commuting. He uses the free time for medical treatments and to rest, easing the fatigue his condition brings. “I was in denial, so frankly it was just wonderful for them to come to me,” Webb says. “I had to go home that day, I was in such an emotional state because of the amazing way they dealt with it.”

At 48, Webb is one of the few people he knows in his relatively advanced stage of MS who is still in paid work, and suspects that, had he been working for a less flexible employer, he’d have been forced into medical retirement by now. “I have young children, an 11-year-old and a six-year-old, so the longer I can keep working, the more sane I can stay, because I’ve got to think about them and their future. And I get to see my children more, too. I can’t kick a football or go cycling with them now, but we get an awful lot of reading done.”

As Webb points out, his situation isn’t unique. In 2015, the specialist part-time recruitment agency Timewise featured him on its power part-time list of people working flexibly in senior positions, and he was fascinated to see how many others were managing something similar. “It’s amazing, seeing all the stories that I just don’t think were possible five or 10 years ago.”

Timewise’s founders, Karen Mattison and Emma Stewart, are, however, quick to stress that things aren’t changing nearly fast enough. Good employers may be increasingly willing to accommodate staff they don’t want to lose, Mattison says, but when they’re recruiting, they tend to fall straight back into the default position: Monday to Friday, 40 hours a week. Few jobs are openly advertised as part-time, meaning that anyone reluctant to work conventional hours can struggle to come back from a career break or switch jobs.

“We’re still relying on the idea that normal is full-time, Monday to Friday, and part-time is what you get as a concession – because you asked in a clever way, or you’re so good that they wanted to keep you,” Mattison says. “What we’re only just starting to do is think: what would we do if we had a blank sheet of paper? What would you actually need to deliver this job?”

They have recently begun a project with five big high street retailers, helping design job shares and flexible jobs at management level so that shopfloor staff – many of whom go into retail because it suits family life, only to get stuck in jobs they’ve outgrown – can climb the ladder without increasing their hours. (The bonus for employers, which include Tesco and John Lewis, is that promoting in-house is cheaper and easier than poaching talent from outside.) But Stewart argues that employers also need to grasp just how many people now want to work unconventional hours, and why.

“There are your classic millennials and younger people coming to us looking for part-time work while they pursue portfolio careers,” she says. “They want to do different things or just don’t want to work in one place only. And at the other end, you have older people needing to stay in work, but wanting to work less, and then a whole range of people in the middle.”

Lately, Stewart says she has noticed rising demand from older women, caught out by an unexpectedly sharp rise in the female state pension age and unable to retire as early as they thought. Part-time work can be a lifeline for this so-called Waspi generation (named after the campaign Women Against State Pension Inequality), who can’t afford to stop work, but may no longer be able to face long working days. But that doesn’t make it easy to find.

Until last year, 61-year-old Francesca Estasy was running her own property management business from home in Manchester, having turned self-employed after being made redundant from her job as regional manager for a plaster manufacturing company. Then she unexpectedly lost a major contract, and started looking for a part-time office job while trying to get a new business off the ground.

Eighteen months later, she’s still looking – a process she calls “soul-destroying”. The few part-time jobs around seem to go to younger women, she says, and many can’t seem to understand why someone her age would even want them: “People who know I’m looking for work have said, ‘Oh, why aren’t you retiring?’ and I have to say, ‘Because I can’t.’ But even if I had my pension, I’d still like to work. I’ve always been busy, I’ve always been a workaholic, and you can get very depressed when you’ve nothing to get up for.”

The jobs she’s now applying for may not be at the level of her old career, but right now that suits her. “It’s on my CV that I was a director, and they say, ‘Oh, this could be quite mundane for you.’ But all my life I’ve been in high-pressured roles, and really I just want to have a job where I can relax.” Having made everyone work for longer, she argues, the government should be doing far more to help this new greying workforce into jobs. For as Britain ages, there will be a growing pool of people who won’t be able to retire and who certainly won’t want to be patronised, but may not want to work in their 60s the way they did in their 40s. And that could have far-reaching consequences.

Last year, researchers from the King’s Fund studying pressures within the NHS were surprised to notice how few GPs in the practices they observed were working full-time. And while the rise in part-time family doctors has been blamed on the feminisation of medicine, with young working mothers supposedly reluctant to put in the hours that older male GPs did, that’s not what the researchers found.

“We’d gone in thinking we would find younger women working part-time, but we found women and men, and also older men,” says Beccy Baird, fellow in health policy at the King’s Fund. “GPs work in half-day sessions, usually a three-hour clinic, and I don’t think we found any working more than eight sessions [four days a week]. Six was much more common and, as they came closer to retirement, dropping down.”

Reducing their surgery hours may well have helped the older male doctors wind down gradually, delaying their retirement. But intriguingly, the trend was even stronger among the next generation of GPs. Only a third of 318 trainees the King’s Fund surveyed expected to work full-time even straight after qualifying, and only one in 10 wanted to do so a decade after qualifying. The most common reason wasn’t family commitments but “intensity of the working day”.

Higher patient expectations, pressure to do more with less money, and the sheer complexity of the cases GPs handle now that nurses deal with more routine appointments have all ramped up the pressure to a point where younger doctors in particular fear burnout, Baird says: “GPs are making quite risky clinical decisions in a short space of time – 10 minutes – and they just felt it wasn’t safe. They don’t work as a team, unlike in a hospital, and they’re holding all the risk. One doctor said, ‘What keeps me awake is that I’ll have missed a blood test result.’” Shorter hours were seen as a way of avoiding dangerous mistakes, and ultimately being a better doctor.

Crucially, many of these part-time GPs are still working in their “spare” time – perhaps teaching, or serving on clinical commissioning groups. But they have learned to mix up the most stressful part of the job with tasks that are a little less life-and-death, essentially rewriting their job descriptions. The growth of part-time working has given them options they didn’t have a generation ago and, like teachers, they’re voting with their feet. But in doing so, they’re creating a potential slow-burn crisis for their employer, the state.

What stops many people reducing their hours is that they can’t afford the pay cut. But in well-paid professions such as medicine, it may not take much added pressure for doctors to decide their time and peace of mind is worth more than money. The fewer hours they choose to work, meanwhile, the more medical students the state must train just to stand still. “If you keep going with a model that is just, ‘Do more of what you do now, but quicker’, then we’re going to need a lot more GPs,” Baird says.

There is a school of thought, however, that suggests that might be a good thing. If doctors or teachers or anyone else has more work than they can handle, why not just train more people to do it, especially in a world where robots may soon gobble up other jobs currently done by humans? Why not just share the work around and shorten the working week for everyone?

When the Green Party proposed a national shift to a four-day week in its last manifesto, it was ridiculed in some quarters. And yet, intriguingly, millions of middle-class working lives are moving in that direction, if more by accident than design.

“I’m not sure what all the answers are yet, but it was about trying to take a step back and ask the question: ‘What is our economy for?’” says Caroline Lucas, the Green MP and party co-leader (appropriately enough, she job-shares the latter role with colleague Johnathan Bartley). “It does seem ironic that on the one hand you have got people working every hour and a group of people who can’t get enough work. And even if it’s exaggerated, it seems clear that automation is going to have a big impact on work. I think that should give us pause for thought.”

The idea that automation could be an opportunity as much as a threat, giving humans more time to relax and enjoy themselves while robots do the drudge work, is undeniably fashionable in tech circles – if only as a way of defusing the backlash against job-destroying apps. Jack Ma, founder of the Chinese e-commerce giant Alibaba, has predicted that within 30 years we could be working as few as 16 hours a week. Facebook’s Mark Zuckerberg has suggested the US will move towards a universal basic income paid by the state to those whose jobs shrink or vanish, a cause also championed by the Greens. Even the famously workaholic Silicon Valley giants are experimenting with shorter working weeks. “It’s interesting that some companies in the private sector, such as Google and Amazon, are now offering their staff that, say, one in four weekends could be a long weekend,” Lucas says.

Yet while Google famously offers engineers 20% of their working time to play around with ideas, company insiders say in reality the scheme isn’t as carefree as it looks (its engineers tend to be so intensely absorbed in their work that they don’t goof off even when given permission). Amazon did trial a 30-hour working week for a handful of office staff last year, saying it realised that conventional hours “may not be a ‘one size fits all’ model”, but it’s hardly famous for the flexibility offered to low-paid staff picking stock in its warehouses.

And when Labour wouldn’t even commit in its last manifesto to reverse the planned freeze on existing benefits, the idea of a new basic income generous enough to subsidise a three-day weekend for everyone looks almost madly optimistic, even though Lucas argues that radical ideas always look impossible right up until they suddenly aren’t: “When the weekend was extended to two days [from one], people said it couldn’t happen. The same was once said of paid maternity leave and the minimum wage. It’s part of a wider debate about the future of work in this country.”

But while that somewhat utopian debate rages above their heads, it seems many Britons are quietly voting with their feet. They’re cutting hours where they can, going freelance when they can’t, and surprisingly often finding that what they thought was a temporary stopgap – just until the kids are a bit older, or until the pension kicks in – has become a way of life. As the saying goes, work expands to fill the time available. But life has a habit of doing the same, which is why four-day weeks can be curiously addictive; once tried, the luxury of a little extra time is hard to give up.

For Stone, the alternative to shortening his hours would have been thinking hard about whether to stay in teaching at all. “The stress really does wear you down. You go in as a young teacher full of enthusiasm and commitment, working all the long evenings and weekends, and actually the turnover of these young staff is so great,” he says. “People want to have a family, or they want to have a social life. They don’t want to be on the verge of a nervous breakdown.” Would anything persuade him to return full-time? “I think things would have to change significantly, in terms of the expectations of staff.”

And right now, the only visible change on the horizon is a squeeze on school funding that may require full-time teachers to work ever harder to plug the gaps. Something, somewhere, may have to give.

The new part-timers

The Waspi woman
So-called after the Women Against State Pension Inequality campaign that aims to highlight the dilemma of women born in the 1950s who, due to changes in the law, saw their retirement age increase with little or no notice. This has left a generation of women in their 60s looking for part-time work to sustain them until they are able to claim their pension.

The low-wage man
The number of men working part-time for a low wage has risen dramatically since the 1990s. Men aged between 25 and 55 who were in the lowest quintile of hourly wages were four times more likely to be working part-time now than they would have been 20 years ago.

The part-time CEO
Chief executives and company directors who work part-time may still be a rare breed, but they’re on the increase, as the Timewise power list shows. The Learning and Work Institute found that the number of people working part-time in senior roles increased by 5.7% last year.

The public sector worker
According to statistics from Timewise, jobs in the health sector, social services and education or training are most likely to be advertised as open to flexible working. Health Education England figures suggest the average GP now works four days a week, and one in four teachers work part-time. But for many in the public sector, unpaid overtime means they’re still working a 40-hour week.

The portfolio millennial
According to the Taylor review, commissioned by employment tsar Matthew Taylor, millennials and centennials are more likely to be in work that is “characterised by contractual flexibility”. This might mean that they are choosing to prioritise their work-life balance, or it could be because of the lack of permanent stability in the jobs market.

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