Tamara Ingram is bubbly, forceful, extrovert and hugely energetic. She is an advertiser's dream - right down to the "It" girl name. Which is just as well, because next month she will become arguably the most powerful woman in British advertising.

This 39-year-old mother of two is about to take sole charge of Saatchi & Saatchi, a name that still resonates in the world of advertising despite the hubris of its proposed £4 billion sterling (€6.4 billion) bid for Midland Bank, the flirtation with bankruptcy at the start of the 1990s and the vitriolic departure of the Saatchi brothers. "The industry thought we would die then," Ms Ingram says of Maurice and Charles Saatchi's departure in early 1995 with about a third of the group's business. "But I never thought the company would go under, because of the culture and the set of values which is owned by the people here."

The most redoubtable executive would find it hard to put a positive gloss on those dark days at the advertising agency. Not Ms Ingram. Sounding suspiciously like a Rory Bremner impersonation of her political hero, Tony Blair, she recalls saying to herself: "But, hey, how fantastic. To be able to do something with this lovely brand. What a lucky girl." Some of those clients who defected with the Saatchi brothers - she cites British Airways - might not, she suggests, have benefited greatly from the switch.

Back to her rise up the ladder of power in which she acknowledges the role of luck. "When I left university I didn't know what I wanted to do. I was incredibly leftwing and was weighing up whether to go into social work or whether to try to make lashings of money. I went for a job in the City but the merchant banker interviewing me just said `you don't want to do this, you should go into the arts'. So I just walked around Soho calling on all the film companies until I got a job with the Wardour Motion Picture company."

After flirting with the idea of television, Ms Ingram found herself temping at Saatchis' Charlotte Street offices in the heart of London's media land, pretending to know about computers. "I fell in love with it, although I didn't expect to. I got caught up in the magic mix of creativity and business."

She explains her total shift of direction with disarming pragmatism. "I believe you can get anything you want - and if not then you just have to change your dream."

Sporting a pinstriped trouser suit and black ankle boots which she happily rests on the arm of her chair as she chats, she easily gives way to laughter. Lighting up one of the 10 Benson & Hedges she "secretly" smokes every day and knows she should give up, Ms Ingram resembles most senior executives in that she clearly relishes being the star of her own story and talks rapidly and intensely about herself.

But, unlike most male bosses, she is disarmingly open about her weaknesses and mistakes. Reflecting the acceptance of being "good enough" which is the lot of most working mothers, she says: "I believe it's perfectly fine not to be 100 per cent perfect. You can lead by vision, hunger and inspiration, and still be a human being. Great leadership is about being able to own up to your mistakes."

She is one of the new breed who hold with the notion that failure has to be acknowledged, even embraced. She argues for a symbiotic relationship between failure, creativity and nurturing ideas. The advertising industry, as well as many others, needs constantly to reinvent itself to keep up with the needs of clients.

"Space and time have changed; we live in a much faster world and we need to deliver everything with speed. But there is a big question about managing time; we need to deliver with speed but we need to create time and space for new thinking and ideas.

"There needs to be a redefintion of what advertising is about. To date we have focused on above-the-line business but the industry is really about ideas, ideas which can be delivered in any medium from Internet to poster. Advertising must become a media-neutral solution."

Ms Ingram, whose first name reflects Russian ancestry rather than Sloanish leanings by her parents, talks passionately about exploring a new way of management. "People are all we have and we have to recognise that we must bring out the best in people - their abilities and their creativity. I think that needs a different style of leadership, a nuturing and coaching of teams, and women are well placed to do that because they are used to juggling different things.

"I do want to succeed with a new style and a new way of working. That's not straightforward, but I want to be able to show that other values have a competitive advantage - things like treating staff well, being more responsible in the community, broader issues like that."

Ms Ingram's leftward leanings are evident in this agenda as they are when she talks about "selling out" by sending her eight- and six-year-old children, Max and Anya, to private schools in Hampstead rather than risk the notorious state system in Islington, where she lives with her husband, Andrew Ingram, a director of public relations group Shandwick.

She is the product of the Hampstead private school system. Now, like so many affluent 30 and 40-somethings, she tries to reconcile the vestiges of a burning socialism and the desire for a comfortable life in inner London. Nowhere is this clearer than in the business of advertising which to many symbolises the waste and artificiality of the capitalist system.

"Advertising is about changing behaviour - we work for the NSPCC, for example. I really don't have many problems with reconciling my politics and work because I believe that everyone should have better education, a better standard of living, better health care, for the north to be as affluent as the south. But to make things happen there has to be change. And advertising does that as well as creating employment in its own right."

Ms Ingram laughs as she says there is nothing she'd like more than to do advertising for the Labour party - a far cry from the "Labour Isn't Working" campaign for the Conservatives which made Saatchis almost synonymous with Thatcher's Britain.

Those were the days when barely a week passed without another acquisition by the Saatchi group. But in 1987, after acquiring Ted Bates Worldwide, then the world's third-largest advertising agency, the Saatchi brothers over-reached themselves. They planned to buy Midland Bank, dreaming of becoming a one-stop business shop for global clients.

The plan's collapse made the brothers a laughing stock with Square Mile pinstripes who had bought the Midas myth while the Saatchis remained in their assigned corporate box. Black Monday and rising interest rates almost put paid to Saatchis altogether. Extinction was avoided only by a series of share issues and the sale of many of the businesses bought so expensively during the 1980s.

The company is reduced to UK number three and consistently tipped as a takeover candidate. Demerged from Cordiant in 1977, Saatchis has pushed up its profit margins and share price. But the City worries that nearly a third of its income derives from two clients - Proctor & Gamble and Toyota. The company's value remains smaller than that of some of its 1980s acquisitions.

Ms Ingram clearly has ambitions for the group, But if she doesn't achieve them, well, she can always change her dream - one more time.