My ads are for Miss Average

MT Rainey came up with the most talked-about advert of the year. She tells Delwyn Swingewood she wants to play her part in changing images of women

A figurine of a Chinese revolutionary guard, rifle in hand, stands in MT Rainey's office. Marxism and advertising are hardly compatible ideologies. MT - the initials stand for Maria-Theresa - says the figure is a memento of Virgin Airline's inaugural flight to Shanghai. MT is joint chief executive of Britain's seventh largest advertising agency Rainey Kelly Campbell Roalfe/ Young & Rubicam. Virgin is one of its oldest clients.

A figurine of a Chinese revolutionary guard, rifle in hand, stands in MT Rainey's office. Marxism and advertising are hardly compatible ideologies. MT - the initials stand for Maria-Theresa - says the figure is a memento of Virgin Airline's inaugural flight to Shanghai. MT is joint chief executive of Britain's seventh largest advertising agency Rainey Kelly Campbell Roalfe/ Young & Rubicam. Virgin is one of its oldest clients.

A newer client is Marks & Spencer. Last April the troubled retailer chose Rainey Kelly to inject a bit of street cred into the brand by giving it a sexier image and get customers buying again. This is no small task. In just two short years, profits for the 116-year-old retailer slumped from more than £1bn to £418m. Matthew Chambers, advertising manager for M&S, says Rainey Kelly won the business, worth an estimated £21m, on the strength of "refreshing new ideas, energy and passion", qualities M&S would dearly like a piece of.

The 44-year-old agency chief has always been brimming with ideas. "It's not just that MT has great ideas about clients' brands. People want to follow her," says Ed Vick, chairman of parent company Y&R, the world's biggest global network with billings of $5.2bn. Her M&S campaign has become one of the year's most talked-about. The 30-second spot, which reputedly cost £100,000 to make, features size 16 model Amy Davis doing a full monty, shouting "I'm Normal". It was designed to illustrate M&S's new sizing, based on a survey of 2,500 women.

"Marks & Spencer was bold to make it," Rainey says. "Clearly we knew it would not go unnoticed because it has only really dabbled in TV advertising before. But we had no idea of the amount of public debate and interest it would stimulate. Six months ago, the newspapers were full of criticism about how the media portrays women as unattainably skinny. Here we are with M&S portraying a woman as being quite realistically shaped. The idea of using this large woman was to say, 'Look. No matter what size you are, things are going to fit you better and you're going to get great clothes'. With this advert we definitely wanted to make a statement that would show women as being confident and beautiful. It's a lovely, celebratory image".

As probably the most powerful woman in British advertising, Rainey has found herself squarely at the centre of the debate concerning the role of media and advertising in particular, which stand accused of creating false body images. "Advertising gets blamed because it's the most obvious - its job is to create images. But the media landscape is immense; TV, film, newspapers, magazines and the internet. In this context, advertising is just one very small part. Such accusations should be directed at the media as a whole, not just one small part.

"I think the extreme thinness of some models is a damaging image. A slender woman is an aspirational image; a skinny woman is not. Kate Moss is a naturally skinny girl and she's very beautiful. Some of the extremes that are used, particularly in catwalk modelling, are stretching the image too far. If you do see some of these people in the flesh - and I think that may be the wrong term - they are seriously emaciated."

The image of M&S has taken a quite a drubbing from the chattering classes. Nigella Lawson, in The Observer, recently stated: "The label is king. And St Michael, unlike St Laurent, doesn't count as a designer tag."

Rainey is unperturbed. She admits to a strong admiration for the brand, having shopped there since childhood. Today she is wearing a chic black trouser suit, an off-the-peg number from M&S, rather than Gucci, Fendi or Versace. "I don't think the average woman has ever worn M&S clothes as a designer label. It's a very quiet brand in that sense. I don't think the average woman is anywhere close to St Laurent. She's certainly not debating between St Michael and St Laurent, unless she's part of the chattering classes in London."

The chattering classes, like advertising, can sometimes mould opinion, but in this instance what the columnists say may be irrelevant. What is important is whether the advertising is successful and effective. Rainey has brought to her advertising career a good insight into human behaviour. She holds a doctorate in psychology from Glasgow University, where she is also an honorary professor.

She began her advertising career in the early 1980s with the legendary American adman Jay Chiat, and was responsible for much of the work behind the launch of the Apple Mac computer. She could have remained in the US, but returned to Britain, along with a slight American accent which hasn't eliminated her west-coast Scottish brogue.

Seven years ago she and three others co-founded Rainey Kelly, an agency with a new modus operandi that turned advertising industry convention on its head. The agency asked clients to pay for the ideas it generated, rather than settle for a percentage of what the client spent on advertising. Observers said Rainey was either mad or brilliant.

Twelve months ago the agency merged with Young & Rubicam's London office, leaving Rainey's team in charge. This year Martin Sorrell, chief executive of WPP, the giant advertising and marketing services group, acquired Y&R and with it Rainey Kelly. "We were very envious when Y&R acquired Rainey Kelly Campbell Roalfe, and disappointed too," says Sorrell. "So disappointed we decided to buy Y&R. It was a big price to pay, but MT and her colleagues are all worth it."

With such a recommendation, things may soon look brighter for Marks & Spencer.