Image caption Erin Gibson Allen (left) got work experience with Judge Lisa Lenihan

When Erin Gibson Allen decided to return to the legal profession after a 10-year absence to raise her children, she knew she would have to get creative.

She took unpaid work experience in the chambers of a federal judge in the US city of Pittsburgh.

"Part of me thought 'what have I done?'," says Ms Allen, 46, who worked for the judge for nine months.

"But the other part of me believed very strongly in experience and networking."

Though Ms Allen says some people were sceptical about her choice, she believed she needed to make an "investment in her future".

Image copyright Getty Images Image caption In Hollywood movie The Intern, Robert De Niro plays a character who goes on a work experience placement in later life

The contacts she made during her internship eventually led to full-time, paid opportunities with a Pittsburgh law firm. She now works as a lawyer specialising in competition law.

"It is a tough jobs market right now, and you have to do whatever you can do to give yourself an edge," she says. "Taking an internship shows how serious you are about getting back to work."

'Different approach'

Internships, or work experience placements, are often regarded as entry-level employment programmes for young people, fresh out of school and new to the working world.

But for Keryn Reynolds, of Melbourne, Australia, and a growing number of similar middle-aged professionals, internships are an appealing way to re-market themselves, and start a new phase of their working lives.

Image caption Keryn Reynolds has swapped policing for journalism

Ms Reynolds, 49, spent decades working for the Australian Federal Police, and then for the Office of Police Integrity in Victoria. After leaving the force, she decided on a complete change, and pursued a new career as a journalist.

She enrolled in a journalism course, and undertook a "challenging" unpaid five-week reporting internship at an English-language news website in Thailand.

Ms Reynolds says her age and experience were a boon to her employers, because they felt that she could handle herself in a way that younger interns might not.

"I think there is a different approach as a mature intern. I'm more than happy to make coffee, or photocopy. or do the basic stuff.

"But I ended up publishing more than 30 stories," she says. "For me it reinforced that I'm resilient and adaptable, even though I am older and haven't done this before."

Ms Reynolds has now graduated with a masters in journalism from the University of Melbourne, and is due to start actively looking for full-time work after she recovers from a foot injury.

Her positive experience of being a middle-aged intern is far from rare, says Marc Freedman, the chief executive of San Francisco-based Encore.org.

Image copyright Getty Images Image caption Actors Vince Vaughn and Owen Wilson played two interns at Google

His non-profit organisation pairs experienced corporate retirees with work in the charity and not-for-profit sectors - both paid full and part-time employment, and unpaid internships.

Mr Freedman says that as average life expectancy has increased in the developed world, there is a growing trend of people wanting to start a new career in later life.

"There is a movement of people who are hitting what would traditionally be retirement age and are having a whole new chapter," he says.

"You think, 'how am I going to live a connected, productive existence for a period that could be as long as midlife in duration?'."

Mr Freedman says this shift is echoed in popular culture, such as the 2015 film The Intern where a 70-year-old Robert De Niro takes an internship at an online fashion site, or 2013's The Internship, in which Vince Vaughn and Owen Wilson play former salesmen trying to get jobs at Google.

'More prevalent'

Anne Gable, 53, of San Francisco, lost her job at business news service Thompson Financial in 2008.

After a three-year stint in art school, in 2011 she enrolled in Encore's fellowship programme, and was paired with Aspiranet, a not-for-profit Californian family services agency.

Image caption Anne Gable swapped journalism for helping unprivileged families

Ms Gable was paid $25,000 (£17,000) for doing 1,000 hours of work over her year-long attachment, during which she helped develop a mobile phone app designed to help kids in foster care keep track of their information

"I think it would have been really hard to find work in this field without the Encore programme," she says. "I don't think it matters what business you're in. At the age of 50 you don't just walk in the door."

Ms Gable so impressed bosses at Aspiranet during her year's paid internship that she now has a full-time job with the organisation.

Carol Fishman Cohen, who runs Boston-based iRelaunch, another body that helps middle-aged people start a new career, says companies are increasingly interested in the experience and maturity that they find in older applicants.

"Some of the biggest and most prestigious companies in the world now run re-entry internship programmes [for older people]," she says, "and we expect to see them become much more prevalent in the next few years."

Corporations such as US banks Goldman Sachs and MetLife, and UK accountancy giant PricewaterhouseCoopers now have internship programmes for older workers.

UK bank Barclays is another, which in 2015 announced its "Bolder Apprenticeships" paid 12-month scheme for prospective employees aged up to 65.

'Fatherly figure'

Unlike their younger counterparts, older interns can find that they are more experienced than the managers they have to report to. "So they can become a sounding board and a mentor," says Encore's Mr Freedman.

That was the case for Dan Hamilton, who was 63 when he retired from a 30-year career in corporate training at computer industry giant Intel.

Image copyright Picasa Image caption Mr Hamilton says he formed a close working relationship with his line manager at the charity

Encore placed Mr Hamilton, of Folsom, California, with local charity Sacramento Food Bank and Family Services, with Intel - which is a sponsor of Encore - still paying his salary.

Mr Hamilton helped unemployed and, often homeless, people search for jobs, write their CVs, and research housing assistance.

He says many of his fellow employees were younger than him by as much as 30 years.

"I felt very much like a fatherly figure," he says. "It was actually more refreshing than in my last few years at Intel, where I was just seen as the old guy."

But whatever the age of someone doing an internship or period of work experience, UK-based pressure group Intern Aware says it is vital that the person is paid, so as not to limit it to people from a wealthy background.

"Internships are a really positive way for people to learn new skills and gain experience in a new profession," says Ben Lyons, Intern Aware's co-founder.

"But it is crucial that people are paid when they are doing work. This is the right thing to do, and also means that companies can get the best people, because otherwise the vast majority of people are priced out."

Back at Sacramento Food Bank and Family Services, Mr Hamilton is now discussing the possibility of becoming a paid consultant for the organisation's chief executive.