Of course I used to smoke, says the woman who helped develop the idea that smoking should be banned in public places. "All political activists smoked."

As a participant in the German feminist movement Kickbusch once sat happily in smoke-filled rooms planning the revolution. Tobacco, she notes, was also a key tool in women's emancipation. "One legitimate way to speak to a boy or man was to ask him for a cigarette."

Kickbusch now dresses in the chic, bourgeois black uniform of the intelligentsia, and her nicotine habit is long over, but the revolutionary spirit remains. The Yale professor's political passion is public health. Sitting in a small, spartan office on the third floor of the Pan American Health Organisation (PAHO) in Washington she ponders the British government's plan to tackle the public health crisis. "It won't work," she declares.

New Labour is notoriously hands-off when it comes to public health interventions. Scared of being seen as nanny-statist, it prefers to leave people to make "informed choices" about their lifestyles. As a strategy for curbing the rise in obesity and smoking-related illnesses, which are set to cost the NHS an extra £30bn by 2020, this is a recipe for failure, says Kickbusch. "We know that for public health strategies we always need a mix of interventions."

The Ottawa Charter, an influential strategy she initiated almost 20 years ago while regional officer for health promotion at the European division of the World Health Organisation (WHO) in Copenhagen, lists the mix that she mentions as government intervention, health information, supportive environments - such as smoke-free public places - community action and a proactive role by health professionals.

Labour modernisers, says Kickbusch have a lot to learn from the interventionist Victorians, who created sewers in response to the public health epidemic of the time, cholera. "We accept that there is a sewage system under the city of London. But in Victorian society the debates were just as heated about why should government do this." It was proponents of the nanny state versus individual responsibility, just like today.

Does she advocate a tax on junk food and banning advertising aimed at children? "The major role of the nation state is setting frameworks, exercising stewardship and setting standards," she replies. "The state has to live up to these responsibilities. We know certain things are more harmful than others for large groups of the population, salt is one, and sugar. So we have to face up to the public health consequences. We can't expect each individual to constantly run around with a calculator. One could set a goal, say that within five years no tin of baked beans would have more than this percentage of salt and no cola drink will have more than this percentage of sugar."

She is credited with turning Healthy Cities - a Canadian model that tackles the social and environmental determinates of health at a local level - into a global movement. "It was the first time that things like housing and work were recognised as influencing someone's health more than the health service," says Dominic Harrison, associate director of Britain's Health Development Agency.

Few people, says David Hunter, chair designate of the UK Public Health Association (UKPHA), have the intellectual rigour, global overview and experience that Kickbusch brings to the field. "She is an important figure to articulate the need for Europe to hold up collective action in public health against the US business-model approach," Hunter says.

Kickbusch, 55, brings her message to Brighton next month when she addresses the annual Public Health Forum, supported by Society Guardian. Her theme is "the end of public health as we know it".

She's not someone to duck the big issues, then? "I'm neither afraid of the big ideas or the vision and strategy to carry them out."

Her starting point in Brighton will be the Wanless report, published last month, which warns that the NHS must be transformed from a sickness service to a sickness prevention service. The report signals progress, she says. "It represents a shift in the way public health is starting to be viewed not as expenditure but as an investment that will save costs in the future. It tells politicians that if you don't address health issues as a whole, a lot of other sections of society are not going to function as well as you'd want them to, or you're going to have a heck of a lot less money to do other things.

"We're understanding a little bit that good public health is absolutely crucial for the functioning of 21st century society with its ageing population and increasingly technological responses to health problems which drive up costs."

Kickbusch was tipped to be the European director of WHO before being offered a job at Yale University's school of medicine. The German minister of health asked Kickbusch to run for the European job, and she couldn't refuse. The French candidate won. There were suggestions that Kickbusch was too radical a contender for the position.

Kickbusch prefers to keep her own counsel and simply draws attention to her achievements at WHO. "I came as a female social scientist into a male medical environment and got to the highest position that wasn't a political appointment."

Isn't she frustrated that despite putting public health on the map two decades ago it is only now that there is a sense of urgency?

"Societies take a long time to learn. It's a societal and political process how a health issue suddenly becomes legit imate and that's what is happening with the obesity area," she explains. "And you ask yourself, 'It's been around for 20 years why has nobody talked about it?' But the same thing happened with smoking," she says.

"Various elements need to come together. It took 50 years to be where we are now from sort of knowing that smoking is harmful to a reasonable acknowledgement and a global treaty."

Its changing nature and intricate link to ideology, morals and economic and political interests explains Kickbusch's interest in public health. Hers is no morale crusade. She is acutely aware of the thin line between promoting health and pushing a kind of "healthism" that could discriminate against overweight people, smokers and heavy drinkers.

Kickbusch points to signals that public health is at last no longer playing second fiddle to curative areas. In Britain, the Wanless report was commissioned by the Treasury and in Germany the government has taken obesity out of health and into a ministry dealing with agriculture and consumer protection.

So is she optimistic about public health in the 21st century? Her reply is unexpectedly stark: "No. I am very worried."

Kickbusch she says she does not yet see the strong government action at a national and global level that is required. "Until health issues and global health issues really are part of the national debate we cannot hope to see much improvement."

The CV

Age 55

Status Has a partner who lives in Berlin and a 21-year-old son

Lives In the US and Germany

Education British boarding school run by Irish nuns, Kodai Kanal, southern India. University of Konstanz, Germany, MA and PhD in political science and sociology.

Career 1974-80: researcher and lecturer in women's studies, University of Konstanz; 1980-94: held various positions at the World Health Organisation European office in Copenhagen, including regional officer for health promotion and director, department of lifestyles and health; 1994-98: director of health promotion, education, communication, WHO HQ, Geneva; 1998: professor of global health at Yale University School of Medicine, department of epidemiology and public health; 2003-04: secondment to Pan American Health Organisation, Washington, senior adviser on Latin America's millennium goals on health.

· Sustaining Public Health in a Changing World - the 12th Annual Public Health Forum - takes place in Brighton, April 19-22. The event is supported by Society Guardian. For more details visit www.ukpha.org.uk