Fresh from battle with cigarette manufacturers and the makers of alcopops, Tessa Jowell is sitting in her spacious Whitehall office sipping mineral water - bottles of which are stacked neatly in a corner desk. Sensing a dangerous line of questioning, the Minister for Public Health (and fierce opponent of smoking) is immediately on the offensive. "We are," she insists, "avowedly against the nanny state. We are not going to tell people how many potatoes they should eat. Certainly there is action for the government to take and it is important that we implement our manifesto commitments. But this job is not about bossy and intrusive government." There will be information and debate but absolutely no "fascist" health policies.

The answers are considered and convincing, word-perfect in fact, and evidence of Ms Jowell's ability to be both, as one friend put it, "seething with New Labour enthusiasm and ideals" and, in the words of another, "brilliantly on-message". Labour's New Women have suffered mixed fortunes in Tony Blair's first government but Ms Jowell is an early victor being tipped (not entirely helpfully) for early Cabinet status.

She faces one or two difficulties along the way. Last week illustrated the unpredictable problems of a portfolio that impinges on the lives and lifestyles of everyone in the country. Her suggestion that the age at which cigarettes can be bought might be raised to 18 dovetailed with moves to reduce the age of consent for gays to 16. The result was a godsend for the cartoonists.

And the fate of her female predecessors at the Department of Health has evidently not escaped Ms Jowell's attention. As one shadow minister put it last week: "Both Edwina Currie and Virginia Bottomley suffered enormously from the nanny image. There is a touch of puritanism and of bossiness about this government. She may well find that brief full of pitfalls."

LIKE Tony Blair, Tessa Jowell was brought up in a middle-class family of Conservative voters. Born at London's Middlesex Hospital in September 1947, the family moved to Aberdeen in the early 1950s when her doctor father, Kenneth Palmer, got a job at the university medical school. The family never owned their home, renting instead, and, as she puts it, "a bit of me always thought we would be on the move". In fact they stayed for years, the houses getting steadily grander as her father rose through the university hierarchy.

Unlike many university wives Rosemary Palmer worked too, also in the Health Service, as a radiographer. If her father was an instinctive Conservative her mother provided a different sort of model, taking a stand against the petty snobberies of university life. "She had a wide range of friends in an environment where there was a strict pecking order - lecturers' wives didn't have coffee with the professors' wives."

The oldest of three siblings, Tessa was used to assuming responsibility, never more so than at the age of seven when both her parents contracted an infectious form of hepatitis and the children either became boarders at school or were farmed out. She attended St Margaret's direct grant school and, while not fulfilling her early ambitions to follow in her father's footsteps as a doctor, won a place at the local university at the age of 17.

After three years reading general arts, psychology and sociology and by then desperate to get away from home, she escaped to Edinburgh University to study for an MA in social administration. At that stage Ms Jowell showed more interest in acting than in politics, but her path towards social work was confirmed by working in Edinburgh's Craigmillar centre where there was an emphasis on helping the underprivileged to help themselves.

She worked as a childcare officer in Lambeth before training as a psychiatric social worker at Goldsmith's College, University of London. After working at the Maudsley Hospital she switched to the voluntary sector, becoming assistant director of the mental health charity, Mind. One long-time friend recalls meeting her for lunch in the 1970s and finding her physically shaking after an encounter with a threatening patient. The experience, however, seemed to make her more rather than less determined to carry on with the work.

But politics was beginning to get a look-in, too. In 1970, recently married to her first husband, Roger Jowell, she was asked to stand in the Swiss Cottage ward of Camden council and did so on the presumption that she would lose. In fact she won and chaired the social services committee at the age of 25. Bitten by the political bug, Ms Jowell was keen, even in the 1970s, to become an MP and contested the Ilford North by-election in 1979. It was an unhappy experience, not just because she lost. The National Front were active, as was the Society for the Protection of Unborn Children, which sent her photos of foetuses. Meanwhile the press was camped outside her front door for reasons other than pure politics: Ms Jowell, having left her first husband, was living with the lawyer David Mills whom she subsequently married.

But her determination saw her through more than a decade of Labour local activism while the party floundered at Westminster. Camden council became identified as one of the centres of "loony Labour". That made Ms Jowell, one of the standard-bearers of what was then known as "sensibilism" - opposition to the uncompromising hard left - the object of attack from those who wanted confrontation with the Tory government. At one meeting, where she backed moves to set a rate, she was at the receiving end of a chicken liver thrown by protesters.

Her stamina paid off 13 years after her first attempt for parliament. When she went for the nomination for Dulwich and West Norwood, a friend told her: "If you want to be selected, you have to want it more than you want anything else". She recalls devoting herself "single-mindedly to meeting as many people as I could. It was toe-curling, turning up unannounced and promoting yourself". It worked, however, and Ms Jowell won by a whisker from Barbara Follett and entered parliament in 1992.

Friends say that Ms Jowell has maintained a family life as well as any woman politician faced with the demands of juggling motherhood and career. She has two children of her own and three step-children; one ally describes her as a "real home-maker". The Jowell-Mills social circuit is a varied one. The couple have a weekend home in Gloucestershire and there are regular dinner parties with guests including Alan Rusbridger, editor of the Guardian, and his wife, Lindsay Mackie - a friend since Edinburgh University days.

Then there are the Camden connections. David's brother, John, was also a Camden councillor, his sister Barbara is the Director of Public Prosecutions. And in London there is a grouping of like-minded Labour women, such as Margaret Hodge, now MP for Barking, and Harriet Harman, Secretary of State for Social Security; when Ms Harman took the brunt of party criticism for enrolling her son in a grammar school, it was Ms Jowell who publicly backed her.

The relationship is not without some sisterly, competitive tension. Ms Harman is a constituent in Dulwich and her own seat is next door. At one point, boundary changes looked more than a little problematic. That episode ended with no disadvantage to either woman. As one friend put it, "there was bound to be friction but the strength of the friendship allowed it to survive the competition".

ONCE IN parliament there was no looking back. Ms Jowell gravitated to the health front bench via the opposition Whips' Office and the women's portfolio. In the former she proved her managerial abilities, dealing effectively with the party's difficult northern male tendency. Her political skills are impressive, her style direct, thoughtful but never patronising. Allies include the influential Peter Mandelson: Ms Jowell was one of only a few outside the Shadow Cabinet to make an appearance at early-morning press conferences during the general election. There has yet to be a significant gaffe and she also gives all the signs of knowing where she is heading. In the words of one source, she has the hallmark of a focused politician: "If there is someone powerful in the room she has an almost subconscious locking-on device".

Of the 1992 intake of MPs only a handful have reached Minister of State level and, of these, Ms Jowell is the only woman. True, within the department, she has a less challenging portfolio than Alan Milburn, one of the other 1992 entrants. But her meteoric rise has fuelled rumours that Ms Jowell is being groomed to take over from her boss, Frank Dobson, a figure more identified with old than with new Labour.

On the surface their relationship seems chalk and cheese; as one insider says: "the woman who rarely makes jokes and the man who tells the dirtiest in the Commons". In fact the two get on better than is imagined; they know each other from Camden council and, in the days before ministerial Rovers, Ms Jowell (who lives in Tufnell Park, north London) used to drive Mr Dobson home after late votes in the Commons.

To opponents, the impression is of an identikit Blairite, what some disparage as the "speak-your-weight-machine" tendency of New Labour politics. That neglects Ms Jowell's lengthy involvement in Labour politics and her clear sense of social justice, driven by a solid faith in the NHS and a desire to tackle poverty and exclusion. At the same time, she has risen in the vanguard of New Labour rather than on its coat-tails.

One fellow Labour MP argues that she is "undeniably able but the question is whether she has the confidence to use her intelligence rather than the six bullet points current at the time".

But breaking free from the Labour machine is probably the last thing Ms Jowell will do after her long battle to reach high office. Ambitious, determined and clever, she knows that the route to the top of Mr Blair's government is no more likely to be through free thought than by adopting the persona of the school matron and instructing the public to eat up its greens.