Have the 20p tabloids shot themselves in the foot?

The casual purchaser at the news-stand last week would have been hard-pressed to distinguish between the Daily Mirror and The Sun. Odd, when the Mirror has launched a hugely expensive price war with its old rival, aimed not only at increasing sales but at doing so through differentiating itself from the Currant Bun.

Not for months have the two titles looked more similar or been in such harmony about the news agenda. Through the week, day after day, the view of both of the country's two biggest-selling dailies has been the same: the biggest story in the world that day was the selling price of each paper – 20p.

Papers obsessed with (usually spurious) exclusives were happily replicating each other's front pages. Papers that usually sneer at any rival publishing "old" news were unabashed at leading on the same story on Friday as they did on Monday and each day between – 20p.

The Daily Mirror, trying not to be a "red top" any more, spent the week looking more like a red top than it has in months. Actually, it looked more like a "red middle", screaming its price in a white 20p on a red background across most of the centre of the front page.

This is a price war, a war between The Sun and the Daily Mirror; between Rupert Murdoch's News International and Trinity Mirror; between editors David Yelland (Sun) and Piers Morgan (Mirror), between traditional red-top content and the Mirror's reinterpretation of the marketplace.

The point, if there is one, of the price war is to increase sale at the expense of the competitor, to get the paper into more hands, so that more people sample it, like it and continue to buy it. But instant retaliation – The Sun dropped its price to 20p on the same day as the Mirror – removes any price advantage of one title over the other, and costs each paper more than £1.5m a week in lost revenue.

True, sales go up, so the costly sampling exercise happens. Sun readers could buy the Mirror as well (and vice versa) for little more than the previous week's full price, but more likely the samplers are people not usually reading either title. The crucial point of this most intense price war for a decade is that it comes at a time when the red-top sector of the market (the biggest) is losing sale more than any other. The average six-monthly combined sale of The Sun and the Mirror is down 179,000 copies on a year ago. The Sun's sale is down 3.4 per cent, the Mirror's 2.7 per cent.

All this may be more about managing decline than preventing it, about market share rather than expanding the market. In Belfast last autumn, at the Society of Editors' conference, Piers Morgan made his redemption speech. In the wake of the events of 11 September he had realised that a paper full of celebrity and TV trivia was yesterday: that in the new world serious reporting and comment were required, even in the popular market. Marketing ploy or true conversion, it grabbed attention.

Morgan, never happier than when in the spotlight, milked it. He hired new commentators, dared to question the conventional wisdom on the war on terrorism, engaged in politics and reminded those old enough to remember of the "golden" era of the Mirror, when the paper's strength lay in providing serious news and debate for the mass market, informing its readers while still entertaining. He removed the red top to the paper; the Daily Mirror would no longer be white on red, but white on black. These were serious times.

The media and political classes were tremendously excited by all this dumbing up, and showered Morgan and the Mirror with awards. But the media and political classes are not the Mirror marketplace, and being talked about by the broadsheets is not the same as being bought by the target audience. The sale of the Mirror fell again last month.

So did The Sun's. But The Sun is not on a redemption strategy and does not believe that its readers have suddenly lost interest in traditional tabloid content. The trouble is, the paper doesn't do it as well as it used to. Yelland's Sun does not have the flair, mischief, confidence or sense of fun that characterised the old Sun of Kelvin MacKenzie. Yelland does not seek the limelight to the same extent as his predecessor – and Morgan – and his paper does not seem as smart.

So when he sends emails to staff full of militaristic language, talking of a "full-scale declaration of war on our rivals", or the need to "take apart the Daily Mirror's business and destroy it", it neither convinces nor amuses. Rather it suggests that Yelland's future is not entirely secure but could be affected by the outcome of the present "war".

In the heat of battle, with their differing and competing philosophies of what brings success in the tabloid marketplace, what have the combatants offered 20p samplers in week one of the war? For a start, much less "new" Mirror than over the past few award-winning months. With page one given over to the price, page three has been regular showbiz and celebrity, albeit more clothed than The Sun's traditional, and current, page three offering. In the Mirror it was bare thighs rather than bare breasts, although the paper's biggest page three pic of the week was of an entirely bare-chested Teddy Sheringham.

The Mirror promoted the "3am Girls", its young showbiz gossip columnists. Double-page spreads each day on Jay Kay being butted, Britney making up with Justin Timberlake, and former All Saints girls Nic and Nat facing the axe. The Sun's Bizarre column (which Piers Morgan once wrote) suffered from less confident projection and writing.

In terms of lead stories there was little indication of two papers with different news agendas. The Mirror was slightly more serious (Byers on Europe, Brit soldiers sick in Afghanistan) than The Sun (Beckham's pay, pro-gress of Siamese twins). And the news agendas themselves hardly differed. Take Monday: Beckham party, the five sisters killed in a house fire, the TV IQ test, the Potters Bar rail crash. All in both papers. And Friday: Byers' euro "leak", Prince Philip on a motorbike, the missing teenager arrest story, the weather. All in both papers. And in terms of columnists, The Sun's Richard Littlejohn vs the Mirror's Matthew Norman. No contest.

The reasons for the price war are clear enough. The strategy is less clear cut, in that both combatants are more likely to lose than gain. The territory over which the war is being fought is most confusing. If the Mirror declared war to expose The Sun's failure to embrace editorially the new climate, then why does it spend week one of the war being less "new" Mirror than it has been for months? Loss of nerve after loss of sale?

The problem with the Mirror's strategy is that unless it takes readers with it, convincing them that old downmarket tabloidism is dead, it could risk giving them to The Sun. And if it tries to move upmarket, into Mail/Express territory, it will find few welcome posters, only another price war with the Express selling at 20p. Only here the rival is so (justifiably) confident that it sees no need to waste money retaliating. But then the Mail's circulation has been upward for years, unlike those of the Sun, Mirror and Express.

Peter Cole is professor of journalism at the University of Sheffield.