At the beginning of June, Professor Diana Anderson set up her very first business: the marketing of her new invention, a blood test that predicts an individual's genetic predisposition to cancer.

After years closeted away in laboratories, universities and libraries, to be the founder and chief executive of a new company, Oncascan, is exciting for Anderson. But she is also part of a wider trend. Now that there is no longer the pressure to retire or the law to enforce it, the number of older women starting businesses is on the increase. Anderson turned 70 just a few weeks ago.

"I'm not proud to have started my first business so late in life for the simple reason that my age never occurs to me," she says. "Until I am no longer able to contribute, I only think of staying at the coalface of my profession. My future plans are to make my business a success, win more grants for my university and guide more of my students towards their PhDs."

Anderson, the chair of biomedical sciences at the University of Bradford, adds that until age "forces me to retire", she has no intention of pottering in the garden, doting on grandchildren or travelling the world. And far from being a disadvantage, she thinks her age is her greatest asset. "I am a better scientist and teacher because of my weight of experience," she says. "Even my newfound entrepreneurial streak is a direct and default result of my age: I couldn't have set up this business when I was younger because I needed all my accumulated years of knowledge to spot the idea and see the gap in the market."

According to figures from Barclays, she is not alone. Older entrepreneurs are responsible for 50% more startups than they were 10 years ago and account for 15% of all new businesses in England and Wales. And life experience does seem to give them an edge: companies started by older people have a 70% chance of surviving the crucial first five years, compared with only 28% for younger people.

It's a change that Bev Hurley, the 58-year-old director of Enterprising Women and employer of an 85-strong workforce, has noticed. "Traditionally, the age when women started up businesses was 30 to 45, but when we started running courses for female entrepreneurs in 2006, we saw an even split between younger and older women," she says. "The oldest woman we have supported was 72 years old."

Children leaving home, mortgages being paid off and redundancy payments or pensions to invest all give older women the means to match the confidence that often comes with age. According to Chris Ball, chief executive of the Age and Employment Network: "Older women entrepreneurs are very interesting. They have the confidence to realise that the experiences they have accumulated – especially the juggling involved in bringing up a family – are all enormously transferable."

Carolyn Hadden-Patten, however, believes that while age has given her a professional advantage it also brings some problems when starting companies. Hadden-Patten ran a clothing shop in the 1980s and 1990s, before retiring. But she found that she missed working so, aged 58, she set up an online magazine for older women, the Weekly Wrinkle. "I'm less able to carry stress and I get tired in the middle of the day," she says. "I worry more and am less brave: I don't sleep as well as I used to, so my mind races at night and I don't wake up refreshed and energetic."

Hadden-Patten is fortunate, however, to have the choice over when she retires. Others must plough on despite – and not regardless of – their increasing age. Hilary Farnworth, a senior lecturer at the London Metropolitan Business School's Centre for Micro-Enterprise, estimates that half of the older women are setting up businesses out of financial necessity.

"If you lose your job after the age of 50, you have a one in 10 chance of getting another," she says. "Living on £66 a week Jobseeker's Allowance plus rent isn't a happy place to be – and there are a lot of years between 50ish and 66, when you can start to claim your state pension. Older women who set up their own businesses are often those to whom life has dealt a serious blow."

Cathy White, 59, whose catering and property businesses collapsed under the weight of the credit crunch, understands this. "My husband and I had been looking forward to retirement. We were going to sit in the garden and hold hands. But just as this wonderful dream was about to become a reality, we suddenly found ourselves weeks away from bankruptcy."

Now White and her 74-year-old husband, Geoffrey, run their local branch of the national catalogue business, Kleeneze. "We dusted ourselves off and started again, and now we're working seven days a week, have 640 customers and are recruiting new staff," she says. "This is not how we wanted to spend our retirement but we're grateful the workplace is flexible enough to give us an opportunity to set up again at our age."

However, experts say flexibility – and employers' prejudice against hiring older workers – must be tackled if the economy is to survive the social revolution under way in British society. Changes in life expectancy mean that one in six people alive today will live until the age of 100. By 2030, the number of people over 50 will have increased to 27 million, or 40% of the total population. It is, says the Office of National Statistics, the most significant demographic trend affecting the size and composition of the labour force for at least the next 15 years.

But it is a highly vulnerable group. According to the Prudential insurance company, more than a third of people planning to retire this year will have incomes below the poverty line.

But the goal of achieving an 80% participation rate among this group is not just to improve their welfare. Economist Christopher Smallwood says it is "crucially important for Britain's economic future". An increase in the labour force of 800,000 – the number of people between the ages of 50 and 65 who say they want to work – would mean that instead of creating a pension and NHS timebomb, Britain's GDP would be increased by about £58bn a year. If even a third of this group returned to work, the saving would be more than £3bn a year.

And opening up the labour market to older people, especially older women, need not involve much upfront funding. "It's not a question of throwing money at it. Older women tend to set up lifestyle businesses: one person on their own. These need an average of just £8,000 to £10,000 startup funding," says Hart. But, he adds, what older women really need is confidence. "They are more likely than older men to say they don't have the skills to set up their own businesses when they actually do. They need specialist mentoring and support."

Hurley adds that older women "have particular health problems and are often facing issues such as the care of elderly parents". They are also more likely to be intimidated by the increased financial risks that come with starting a business late in life – a business which you then have only limited time to create and grow.

Even if specialist funding, advice and support is available, some fear that the older woman entrepreneur might be a historical anomaly. At 62, Patsy Seddon is on her third business startup. Seddon, who sold Phase 8, her own fashion label, in 2005 for £28m, recently launched the online fashion retailer Shircket.com. "We were 1960s children, who came of age in a time of quite extraordinary energy, optimism and possibility," she says. "It was easier to get childcare and, because we had babies when we were so young, we still had energy to throw into our professional lives when they were grown up.

"Life for women now is much more confused. Everything is happening later. Women are waiting so long to have babies that they don't want to work when it finally happens – and then they're too tired to return to work after their children have left home. It would be a great shame for women and for society, but I think there's a real risk that the older businesswoman is a wonderful but momentary glitch."