Jennifer Mindell has a mission. She wants to make life for the tobacco companies as uncomfortable as she can.

For two years running Dr Mindell, a public health physician who has become one of the industry's most persistent opponents, has reported more than 80 per cent of the breaches of the Voluntary Agreements on Tobacco Advertising and Sponsorship: 22 of 27 successful complaints in 1991, and 30 out of 31 this year.

Modestly, she refuses to take most of the credit. 'Monitoring of the agreements is virtually non-existent,' she says. 'It relies on complaints from a public that finds the agreements difficult to get hold of and impossible to understand. So it's not that I'm doing such a lot; more that so few others are doing anything.'

Breaches of the tobacco advertising agreements are certainly no rarity. After a single foray along a half-mile stretch of Cowley Road, Oxford, Dr Mindell made successful complaints about 15 of the 145 cigarette advertisements she found. And in a brief tour of a Watford suburb one Sunday morning, she and I discovered cigarette advertisements without health warnings in two of the three shops we visited.

Extrapolating from her results at Oxford, where she headed the Keith Durrant Cancer Prevention Project (an educational project based at the city's Churchill Hospital) until her family's move to Nottingham, she estimates that at least 70,000 breaches a year occur nationwide, with a detection rate of less than 0.05 per cent. 'There is a minute chance of detection,' she concludes, 'unless it happens to be near where I live or work.'

Dr Mindell believes that the actions of Comatas (the Committee for Monitoring Agreements on Tobacco Advertising & Sponsorship) have the effect of keeping complaints figures down - hardly surprising, she says, given that half its members are drawn from the tobacco industry, with the balance being made up of civil servants.

For example, although 18 of her complaints from the 1992 report period (running from June 1991 to June 1992) are awaiting a ruling, half of them acknowledged by letter, a total of six complaints were listed in the report as 'still under investigation'. 'The figures just don't add up,' says Dr Mindell.

And, she warns, 'You must send in a photograph with every complaint, or the answer is often that 'it was not as described at the time of our visit'.' She says that another factor that reduces public confidence in Comatas is the manner of investigation: each tobacco company investigates complaints against itself.

'Even when a complaint is upheld, there is no sanction or penalty. All that happens is that the offending ad gets replaced with a newer, shinier, glossier one.'

The agreements, says Dr Mindell, are failing to control tobacco advertising. 'Those who say voluntary agreements are the best form of control are right: they are best for the tobacco industry. No one with a detailed knowledge of the agreements could possibly support them as being for the public's benefit.'

With the Royal College of Physicians reporting that 450 children take up smoking every day, the agreements may also be failing in one of their principal purposes: to protect children from tobacco advertising. This, Dr Mindell suggests, is no accident. 'Studies show that 60 per cent of smokers start by the age of 13, and 80 per cent by 16. So the cigarette companies know where to recruit the next generation of smokers. Whether or not they target children is irrelevant. What is important is that children notice, remember and are influenced by tobacco advertising.'

The Gallaher Silk Cut poster featuring a rhinoceros in an opera hat is especially attractive to children, she says. 'Animals are very appealing to children, and this rhinoceros in particular appeals to a child's sense of the ridiculous. Even my own children say, 'Yes mum, I know that smoking is disgusting and bad for you. But what a great poster]' '

She is livid at the Advertising Standards Authority's response to her letter about that poster. 'I just can't believe it,' she says. 'They said they didn't think it was likely to attract children and dismissed the complaint.'

'What about the new one with the swordfish in silk knickers?' I ask her son William, aged six. 'That one's even funnier,' he smiles.

Protecting children is Dr Mindell's highest priority. 'I want to do everything in my very limited power to protect children from the lure of the industry's glamorous advertising. I believe they have the right to grow up free from the pressures of tobacco promotion.'

But what inner force is driving Mindell's crusade? A desire to protect her son and eight-year- old daughter must play its part, as must her hospital experience of caring for people with smoking- related lung cancer, amputated legs, peptic ulcers, heart attacks and severely disabling bronchitis. But in these respects she is hardly unique. And, she remembers, 'I was already strongly anti-smoking as a teenager.'

Suddenly it comes to her. 'Moral outrage, that's what it is] I'm outraged that the tobacco multinationals are making more than a billion pounds a year peddling lethal products. The industry has known for more than 30 years that its products kill. It has responded by promoting tobacco more and more intensively and effectively. The time has come for this to stop.'

The Government's reluctance to ban tobacco advertising strikes Dr Mindell as deeply perverse. 'Tobacco is unique: the only consumer product that is lethal when used as intended. As such it requires unique treatment. The Government's failure to impose a ban seems to be based more on friendship with the tobacco companies than on the evidence before it. Every month of delay means thousands of children starting an addictive habit that will kill or disable them.'