INNOVATION:Anita Roddick is the most influential business leader of the last thirty years. Discuss.

This was an exam question for a mock A-level paper taken by 18 year olds in the UK in January, 1997. The reason it sticks in my mind is because I was the teacher who set it.

This took very little foresight, as Roddick was by then one of the most famous business people in the world. Even my students had heard of her. It was a toss up between the Queen of Green or Richard Branson.

However, now green is the new black and recognition for Roddick in leading the way on environmental issues grows with each passing year. But this is only one part of it. Roddick's influence goes much deeper than that.

I'd been an admirer for a few years, relying on her to liven up lessons that suffered from a teaching style that was not so much Dead Poets Society as well, dead. Every month or so, I took groups of semi-literate, over-sexed 18-year-olds out of college and headed for The Body Shop factory on the south coast of England.

The company laid on a tour of its HQ, which was interactive and fun and told the whole story from the opening of Anita's first shop, which started as a means to make money while her husband chased his own dream of trekking across America on horseback. We learned about the significance of sourcing raw materials, about fair trade practices and that it was possible to make money and still try to be ethical.

One time, the lady herself appeared from an office just up the corridor and seeing the students, ran over and gave an impromptu Q&A. The kids were enthralled. She was funny and sexy and had a charisma that meant you couldn't take your eyes off her. Her eyes flashed as she told us about the Ogoni tribespeople in Nigeria who were being driven from their land by Shell's rapacious oil exploration. She told us that the tribe's spokesperson, Ken Saro-Wiwa, and eight others were executed by the Nigerian government, but that, eventually, 19 others were released. As we left the factory, we saw a huge sign berating Shell placed strategically opposite one of their petrol stations. We talked about nothing else all the way home.

A few weeks ago, on what would have been her 65th birthday, 1,500 people attended a remembrance service in Westminster - Roddick, by now a Dame, died of a brain haemorrhage in September last year.

The ceremony was followed by a march across the Thames to the National Theatre, on the South Bank opposite Big Ben. Her picture was beamed onto the side of the National and 5,000 bio-degradable balloons were released into the air, sent on their way by a gospel choir.

Every person in the crowd wore a t-shirt with the words "I am an activist", reflecting Roddick's mantra: "This is no dress rehearsal. You've got one life, so just lead it and try and be remarkable."

The image of those balloons came back to me last week, at a very unexpected time and place.

I was sitting in the lobby of an achingly trendy advertising agency in Soho - all exposed brickwork and Pete Doherty pork pie hats. I'm invited up to a boardroom, past a room where a man was lying in a pool of plastic balls. "We go there to think," said the Scarlett Johansson look-a-like leading the way.

I sat down with some other assorted journalists to watch a presentation on "the way forward" for the marketing industry. What followed was a chin stroking diatribe on "the future of brand".

The content of the presentation was pretty much what Anita Roddick was saying and doing in 1977: the brand is a platform around which the company can campaign on issues that will come to define it. The best brands have always been the best storytellers. We engage with stories because we have listened to them since we were painting in caves.

Roddick's genius was to marry her gift for narrative to her passion for the environment and fair trade. Body Shop was not about shampoo, it was about ethical consumerism, the fight against Aids and putting pressure on governments to focus on poverty.

We bought the foot lotion because we liked the idea behind it. Looking back, my exam question was a fair one. Anita Roddick may have been the most influential business leader of her generation. It's just that we didn't really know why.