PresentTense: Who could have predicted that Britain's newspaper wars of the early 21st century would centre on pictures of cheese? But so it has come to pass that wall charts - featuring everything from assorted lettuce to life-size prints of the human body - have been the great giveaway success of 2006. It means that this week, for instance, the biggest headline on the front page of Wednesday's Guardian featured one word: "Crops".
Inserted inside was a full-colour wall chart (admittedly that colour was largely green) featuring pictures of kale, borrage and fodder beet, complete with their Latin names.
In keeping with the attitude of the Guardian, it included a rather striking image of Industrial Fibre Hemp (Cannabis Sativa, as if you didn't already know) and for one day at least, the Guardian could be accused of smuggling dope into Britain's schoolrooms.
The crops wall chart was one of a series that this week also included Cattle, Sheep and Poultry, and Waterfowl. For a bookish farmer with a lot of wall space this must have been the week he thought would never come.
Indeed, The Irish Times has had great success in recent times with the posters that accompanied supplements on subjects such as trees and demographics. But last month saw an acceleration during which the Guardian and the London Independent each ran posters on the same subjects on the same days. For one week the soul of the reader was being decided by which newspaper had the most comprehensive poster of tomatoes, apples and cheese.
As one correspondent to the Guardian suggested: "All I need now are charts showing varieties of bread and pickle, and I'll have a ploughman's lunch." The frenzy dragged in other protagonists. The Daily Mail lobbed in a wildlife poster. But the Guardian was first to acquire what, in the wall chart arms race, is the equivalent of the Bomb: a giant poster on the subject of "Salad Greens". It was an idea so audacious, so utterly preposterous, that it became an instant collector's item; an object which marked the day the newspaper marketers entered a kind of madness. When the future of a 180-year-old institution hung on the drawing of a leaf of lollo rosso.
Simple, edifying yet laced with irony, the wall chart has delivered a sales spike. Possibly because of its appeal to bulk-buying schools, the Guardian's circulation rose more than 7 per cent in September alone, although it sagged like a soggy salad green the following month. Buoyed, the paper has since taken to giving away free stickers of dinosaurs and wildlife: a literal approach to throwing an idea at the wall to see if it sticks. If it confirms that the valuable youth demographic now reaches as far as readers who have yet to reach double figures, you also sense that there are a more than a few grown-ups opening their briefcases each day to reveal a fearsome ankylosaurus stuck to the interior.
The impression is that the wall chart craze is about to pass, at which point there will be a search for another idea to tempt a broad age-range - and their schoolteachers. Free temporary tattoos featuring the giants of English literature, perhaps.
But some day, someone might do a wall chart on the evolution of the newspaper giveaway, and this retrograde fashion will be an anomaly; a little like a shrew suddenly turning up as the missing link between ape and man.
Until now, the giveaways were becoming more technologically sophisticated. The free CD made its appearance in the Mail on Sunday in 1998, when the paper gave away football-related music to coincide with that year's World Cup and its circulation rose by 10 per cent for that day alone. By 2000, it was becoming commonplace for a paper to come with anyone from Cliff Richard to the Sex Pistols glued to the front page.
By last year, as many DVDs were bought as part of free newspapers as were sold on the British high street: at least five per household. In the first half of this year, 54 million were given away. They can be added to the free teach-yourself-Spanish CDs and plethora of books.
Giveaways have been the industry's Viagra. One good day lifts the rest of the month, but they are a stalling tactic at a time when newspaper circulation continues to fall; a psychological boost to a sagging industry. Even the Sun's 18-rated DVD at the end of October couldn't perk it up. Its circulation is at the lowest point for 30 years.
Besides, flooding the market with freebies has also loosened the loyalty of readers, who go from one Viagra-popping paper to another. And it has devalued any newspaper that doesn't arrive with a lucky bag of goodies. Last December, the Guardian's marketing director forecast the end of the trend for free DVDs in 2006, saying: "I think it will go back to the marketing of journalism." He was wrong. Although if he'd said that it would be about the promise of a nicely reproduced gorgonzola, he might have been told that that was an idea he couldn't give away.