Charity Kirigo Kimani worked long hours as a nurse at the national hospital in Kenya, finding it extremely difficult to make ends meet.

A mother of three, she did not see a bright future for her children if she stayed in Kenya - so she applied to the NHS, which was looking for nurses.

"Salaries in Kenya were very little," she said. "Everyone had to have some side business - selling cotton wool, cooking, doing some other work at home - and it was very difficult to make a living. I had to take action."

Ms Kimani came to England in 1995, just as staff shortages were beginning to hit the NHS. Between 1990 and 1997, the number of people coming into the nursing profession in Britain fell from 18,980 to just over 12,000.

Nurses recruited from abroad accounted for 26% of the 16,000 nurses registered in 1997, and five years later that figure had grown to 43% of the registered total of 37,000.

Many came from the Philippines, South Africa and India. Even though the number of African nurses was relatively small, it nevertheless represented a large proportion of the health workers in their countries.

Life wasn't easy for Ms Kimani when she came to Britain, but she had access to a superior infrastructure and modern techniques.

She had to endure some humiliation from patients, who questioned her competence because she had come from Africa, but she saved enough money to send her children to university and to buy property in both the UK and Kenya.

Last year, Ms Kimani moved back to Kenya. "I had a target to help my children get a good education," she said. "Once I knew they could stand on their own, I decided to go back."

Now in Nairobi, she is working to raise £437,000 to set up a telephone-based counselling service, HIV Helpline, to offer advice to families living with HIV, and plans to recruit 20 workers.

Her story humanises the debate about healthcare professionals in Britain. It shows what is happening at the micro level at a time when the macro outlook appears so dismal.

Nevertheless, organisations such as Save the Children are critical of the influx of nurses from developing countries.

"Many African countries have limited funds available for health," Mike Aaronson, the charity's director general, said. "Vulnerable children suffer disproportionately when these services are failing. It is shameful that many poor countries are spending millions of pounds training nurses and doctors to prop up the NHS."

The crisis is acute - around 36 African countries do not meet targets of one doctor per 5,000 people, according to the World Health Organisation.

Even in non-conflict affected countries such as Zambia and Ghana, there is only one doctor per more than 10,000 people, while disparities are evident within a country such as Kenya. In Nairobi, there is one doctor for 500 people, but in Turkana district the ratio is 1:160,000.

Aware of the criticism, the NHS has adapted a code of practice that bans it from actively recruiting staff from developing countries. But it needs workers - and thousands of people living in poor countries want to work in a better environment.

It is true that Africa's health sector needs more resources, but those resources will not become available by preventing skilled workers such as Ms Kimani from coming to Britain.

What's often left unsaid in this debate is the role of emigrating British nurses. That poses the moral dilemma that if a UK-trained nurse is free to leave for the US, Canada, or Ireland (the three most desired destinations) - and even beyond, to the Middle East, Australia and New Zealand - why shouldn't Ms Kimani and her compatriots come to Britain?

There has been a remarkable increase in the number of British nurses moving overseas. More than 2,000 left for the US last year, a quarter of the 8,000 who left the country overall. In 1997, the number of nurses who went overseas was half that.

Overseas recruitment is not the only reason African health workers leave their home countries. For many, there are simply no available jobs.

"When I was studying in Kenya, we were absorbed automatically," Ms Kimani said. "Now there are more nurses than the country needs or can pay for. If all the Kenyan nurses who work in the UK were to return to Kenya, there won't be enough jobs for them ... I am not betraying my country."

Forcing people to stay at home will not work. As Kwadwo Mensah, Maureen Mackintosh and Leroi Henry write in The Skills Drain of Health Professionals from the Developing World, a paper published by the UK charity Med-Act: "Coercive measures to prevent departure work poorly; worse, they can intensify pressures to leave."

There are inequities in this dilemma, but remittances partly mitigate the situation. According to the World Bank, migrant workers send more than $90bn (£44.7bn) to their home countries, the second-largest source of funds for poor countries after foreign direct investment. It is a significantly higher amount of money than that provided by development aid.

Health charities acknowledge the power of remittances, but remain critical because such flows go direct to families and do not replenish the loss suffered by the state in providing the subsidy in the first place.

With that in mind, the economist Jagdish Bhagwati, of Columbia University in the US, says states should tax their citizens who work and live abroad - something the US already does.

Several charities have argued that the UK should provide financial restitution and fresh development aid to Africa so that it can bolster its health sector. However, developing a grand plan would take time.

That is why individuals such as Ms Kimani are so important. Granted, all emigrant health workers may not return home, but their remittances lift their families out of poverty.

What can be done about the skills gap? "Skilled Africans are going to emigrate. I would propose a Grey Peace Corps, where our ageing and early-retired skilled professionals can be tapped for two and three-year stints to work in Africa," Dr Bhagwati said.

"While Africans, whom we must train in vastly increased numbers at our universities, will work here, our people must work in Africa until the need for skills can be met meaningfully."

· Salil Tripathi is a London-based writer who specialises in Asian and international economic affairs.