They've changed the face of our high streets. They've seen off the cosy one-to-one relationships we used to have with the grocer, the baker, the candlestick-maker and all the rest. They've made us a nation of out-of-town one-stop shoppers, content to fill our trolleys with everything from a bag of sugar to a garden hose in the impersonal atmosphere of the superstore. Now the supermarkets are turning the heat on the women's magazine market, threatening titles such as Good Housekeeping, Family Circle and Prima by offering their own-brand titles, which are glossy, expensively produced and have pride of place on the checkout news-stands.
For the traditional magazines, which sell for the best part of £3, the supermarkets offer competition they could probably do without. In 1997 the top five titles were selling a combined total of 5.4 million copies. That dropped to 3.5 million in 2002 partly due to the competition from television programmes about lifestyle and makeovers.
Now the influence of the supermarket titles is becoming apparent. The latest figures from the Audit Bureau of Circulations show that Asda magazine has a circulation of 2,266,760 and is now Britain's fourth biggest title (Sky's magazine heads the chart). Safeway and Somerfield are also in the top dozen and Sainsbury's Magazine (a paid-for magazine and the first to launch, in 1993) and Waitrose are all big players. Tesco has now launched a title.
We know they're all about selling the brand. We've heard about the Delia factor where every time Delia Smith features a new recipe, the ingredients simply fly off the shelves at Sainsbury's. But the influence of the supermarket magazines has crept up on us. Suddenly we find that the market is worth a staggering £313m, according to the consumer market research group, Mintel. Latest ABC figures show a 12 per cent growth in the consumer magazines market and 10 per cent of that growth is customer magazines.
Julia Hutchison, the director of the Association of Publishing Agencies, attributes the rise of the supermarket titles partly to their ability to target readers - thanks to the vast amount of knowledge and data gleaned from credit and loyalty cards. "It's a very sophisticated system," she says. "They know a great deal about their readers - what they buy, how they live - so their targeting is precise."
She also points to the quantum leaps in editorial quality that many supermarket magazines have made. "Customer magazines are very effective in growing brands. Historically they are seen as a poor relation to the glossy women's monthlies but now many of them are as sophisticated as any other magazine," she says.
There's no doubt that supermarket magazines have taken several pages if not sections out of their glossier sisters' books. Now you can find lifestyle sections, hair and beauty pages, gardening information and health guidance in Asda, Safeway, Somerfield and Sainsbury's magazines. It's all there to market the particular supermarket's products of course, but clever design and layout make the pages as attractive as a paid-for magazine - and apart from Sainsbury's Magazine, which costs £1.50, they're all free.
Juliet Warkentin has worked in both sectors. A former editor of Marie Claire magazine, she is now the editorial director at contract publishers Redwood. "They all have dedicated teams. They need to get right into their brands. Safeway magazine for example has a staff of nine including an editor and art director and a stable of regular freelance writers. They are incredibly professional and competitive," she says.
The editors of the "big five" titles in the section of the market most under threat from the supermarkets - BBC Good Food, Essentials, Family Circle, Good Housekeeping and Prima - are keen to differentiate their products from the in-house magazines. And the circulation figures suggest they are fighting their corner. Gillian Carter, the editor of BBC Good Food, says that her circulation of 342,000 paid-for copies at £3.50 each has been earned by a reputation for independence and expertise.
She says: "You can always argue that people don't necessarily perceive great value in something that is free. When people make an active decision to purchase Good Food it's because they believe in us and trust in us.
"If we do a 'tried and tested' we select a variety of brands and look at what is available in different supermarkets and our experts will come up with what's best."
Carter admits that the quality of editorial in supermarket magazines has improved and the design is good but believes that consumers are not fooled. "Consumers are quite canny. They know all the products will be from that supermarket and that's limiting. These magazines are part of a huge ever-growing women's market. They are no more of a threat than the newspaper Saturday supplement."
Sue James, the editorial director of IPC's women's lifestyle group, whose stable includes Family Circle and Essentials, agrees. "It's a different relationship with a reader when you pay for it. In the research we have done with focus groups I've never heard a reader saying 'I don't buy Good Housekeeping or Essentials because I'm reading Tesco magazine. When you pay for it you bond to it." She bristles when she is confronted by the sight of supermarket magazines dominating the circulation ratings. "I get really furious when I see these charts. There's a lot of difference when you have to put your hand in your pocket. I don't see them impacting on consumer magazines. Women are very discerning these days."
James complains that the supermarket magazine has an unfair advantage in terms of display. "I see them as a threat in terms of news-stand and availability. They are on every checkout. There's a real pinch on space here. Like every other publisher we are negotiating on this. It's like putting your hot-spot seller in the shop window."
The fight for a decent position on the news-stand is as fierce as the competition for readers because the brutal fact is that fewer people are reading magazines. Supermarket magazines care less about circulation than they do about readership. That's what attracts outside advertising, although not all of them accept ads other than for their own products.
Juliet Warkentin, whose company produces Safeway magazine, says the possibilities for supermarket magazines are endless. "We only need to look at the [yearly] turnover of the likes of Tesco [(£25.7bn], Sainsbury's [£18.2bn] and Safeway [£9.4bn] to get an idea of the influence of the supermarkets on consumers and on consumer spend."