“I’m into my fifth week now: I’m a newbie!” says 60-year-old Andy Barnard, who was a regular customer at his local Co-op in Lincoln before the manager suggested he apply for a job.

“It ranges from working on the tills, on the shop floor, stacking stuff and just generally doing everything,” he says of his new 16-hours-a-week role.

After 45 years in bricklaying, from which he retired in March, it’s taking Barnard a while to master the hi-tech tills and lottery machines. But he is enthusiastic. “All the girls and the staff they just take the mickey all the time, which is great fun. You get the regulars coming in and it’s good banter.”

Living locally with his mum and their four dogs, the money Barnard earns helps him avoid dipping into his savings.

During the pandemic and its aftermath, thousands of older workers left their jobs – whether for health or family reasons, or a straightforward decision to retire.

The sharp increase in economic inactivity among this age group concerned policymakers, coming at the same time as employers reported struggling to recruit suitable staff.

Official figures suggest some of those people are now returning to the workforce, whether through choice or financial necessity.

The number of 50- to 64-year-olds who are economically inactive has fallen by an estimated 129,000 since its peak in mid-2022, and the inactivity rate among over-65s is down modestly too.

Barnard’s employer, Lincolnshire Co-operative, founded in 1861 on the same principles as the UK-wide Co-operative Group, is keen to attract and retain older staff, offering flexible hours and a straightforward recruitment process using phone interviews. Of its 2,900 staff, 27% are over 55.

Among them is 79-year-old Colin Lane, who has worked at his local store for two years.

“I just walked over there one night to get my bits and pieces and there was a sign outside: part-time staff wanted,” he says. “And I thought, OK, that’s nice, I’m 77, nobody’s going to employ me. And then I sat and thought about it and I thought, nobody will employ you unless you actually ask.

“I put my application in and no one was more surprised than me to actually get the job. And I have loved every minute of it.”

Lane returned to the UK during the pandemic after a period living in Portugal. He doesn’t need the money from his 18 hours a week on the shop floor, but the extra cash does allow him to run a car. And like Barnard, he appreciates the personal interaction involved.

“I needed an excuse to get out of the house, and what better excuse could you have? It’s got me out meeting people. My mind is more active, my body is more active, and I hope to keep going for as long as possible.”

Among other older workers who have “unretired”, the deteriorating economic outlook has been a factor.

Alan Bremner, who is 57 and lives in Glasgow, took an early retirement in 2021 from the insurer Zurich, but recently returned to his former employer after becoming concerned about his finances.

Bremner took advantage of rules introduced by George Osborne that allowed people to access their pension savings from the age of 55.

“I was lucky enough to have a couple of final-salary pensions and after taking a lot of quite expensive financial advice I was given the go ahead to say that yes, you can take one of these final-salary pensions and basically take the transfer value of that and convert it into a drawdown pension,” he said.

That meant reinvesting the funds from the pension, which he expected to provide him with an income until the age of 60. But he and his financial adviser reckoned without the actions of Vladimir Putin – or Liz Truss.

“I stopped working in January last year, and that turned out to be probably the worst time in the last 10 or 15 years to do that,” Bremner says.

“Russia immediately invaded Ukraine and because the pension’s invested in the stock market that immediately dived. Then we had Liz Truss and the cost of living increases, and inflation as well.”

Initially, he enjoyed his retirement. “I wasn’t doing anything really exciting – we hadn’t gone off on a round the world trip or anything – but I was perfectly happy just having a relaxing time.”

But he became increasingly worried about the financial implications of his decision. “The sum of money that you’ve got to live off basically dropped by about 20%.”

After a year or so, Bremner decided to take up the offer of a former colleague at Zurich to return to work part-time.

He now works two days a week in Zurich’s Glasgow office, as a claims technician – helping to assess third-party motor claims – and enjoys using his two decades of experience. “It helps to have an older person who can sit in the corner and dispense advice.”

Zurich’s head of HR, Steve Collinson, says the company has a policy of advertising every role as potentially being part-time or a job share.

“We’ve got a view that flexible working is both the antidote to the older worker exodus and the key to attracting older workers to join us,” he says.

“We’ve got a really healthy-sized part-time worker cohort, and when we talk to our part-time workers who are in that later stage of their career, many of them are still interested in things like career development. If they don’t think there is a culture of celebrating flexibility, then it holds people back from applying for things like promotions or different opportunities. When you put this flexibility at the core, it removes that conversation.”

Dr Emily Andrews, of the campaign group the Centre for Ageing Better, cautions against overinterpreting the modest fall in inactivity among older citizens.

“To me the main story is: pre-pandemic you had years of increases in the employment rate among the over-50s, which then the pandemic has stalled,” she said.

She says the inactivity rate for 50- to 64-year-olds remains well above that for younger workers – 26.5%, compared with just 11.9% for 35- to 49-year-olds.

“People in their 50s and 60s do not have fair access to work right now,” says Andrews. “You’ve got structural barriers – things that can impact anyone at any age, and don’t just impact people in their 50s and 60s, but are particularly likely to happen at this age. That is things like having a long-term health condition or disability, or having a caring responsibility.

“Then you’ve also got ageist attitudes – both the ageist attitudes that other people have towards us, and also our own internalised ageism.”

In response to concerns in government about the UK’s “missing workers”, the chancellor, Jeremy Hunt, announced extra funding to help over-50s back into employment in his March budget.

But campaigners said much of this involved “signposting” people to existing schemes, rather than new support.

A government spokesperson said: “We are helping grow the economy by supporting those who want to work, including older workers, to do so.”

The work and pensions secretary, Mel Stride, made his own contribution to the debate earlier this month, visiting the headquarters of food delivery company Deliveroo and suggesting the flexibility it offers might suit older workers.

That claim was rubbished by the Trades Union Congress, which accused Stride of “glorifying” a model in which much of the flexibility lies in the hands of employers, not self-employed riders waiting outside takeaways on mopeds.

Back at the Co-op, five weeks into unretirement, Barnard has no regrets thus far. “It is that getting out and meeting different people and speaking, and it’s great – I love it.”