In the first exhibition of its kind to open at the Victoria & Albert Museum for 67 years,there is a poster of Gary Cooper. The lean- faced, lantern-jawed, long-legged hero is holding a voting slip instead of a gun and striding forward determinedly, wearing a political badge on his lawman's waistcoat. Against the white background, a distinctive, blood-red Solidarity logo fills in the necessary context. This poster is in fact nothing less than a piece of instant political history, a call to Poland's population to fulfil an urge to democracy first acted upon in a single shipyard in Gdansk.
"It's probably my favourite of all the posters in the exhibition," confesses the curator of the V&A's "The Power of Posters" exhibition, Margaret Timmers. "It's really an expression of longing: a longing for freedom and for memories of the past to be forgiven and forgotten."
In the next room there is a poster of Eva Herzigova. The lean-faced, quite possibly long-legged heroine is wearing a skimpy black Wonderbra, matching panties, and as far as my extremely careful examination could make out, no political affiliation whatsoever. Against the white background a two word logo - "Hello Boys" - fills in a rather less necessary context. This too, I suppose, is an expression of longing: even if it is of a rather different sort.
That's the beauty of posters. Nowhere else in the media is the customary gulf between the medium and the message so summarily disregarded: nowhere else is the difference between potential and practice so pronounced. Execution is everything.
The V&A show makes this abundantly clear as it traces the history of posters over the past 120 years. It divides the work thematically into three sections. The first of these is Pleasure & Leisure, which ranges from the sublime artistry of Toulouse Lautrec to the no less sublime montage of tawdry tat which the Sex Pistols used to promote their Never Mind The Bollocks LP. Next up is protest and propaganda, which runs from Gary Cooper to Kitchener's wartime recruitment drive. Commerce & Communication, on the other hand, takes in Bovril's weeping cow with its fantastic slogan "Alas! my poor Brother" and the pick of the current crop.
"The first reason for putting on the show now was that our last big poster show was in 1931," explains Timmers, "but also because posters are becoming more important as other communication fragments. Here is this fluid, flexible medium that can adapt and change to explain the way we are."
Certainly her selection helps explain why posters are big business and getting bigger. This year, three quarters of all advertisers will use the medium; seven years ago that figure was just 35 per cent. The story of posters in this country prior to that time was a story of dodgy men in suits drinking heroically and managing a gentle decline. Now the medium is awash with multinational expertise and experience - revenue last year was up by 12 per cent at pounds 480m and one of the leading companies, More O'Ferrall, is currently being fought over by warring predators who have already forced the price up to an impressive pounds 475m.
"The single most expensive regular poster site in the UK - along the Cromwell Road in London - now costs around pounds 40,000 a month, and for a typical two-week national advertising campaign you're unlikely to get any change out of pounds 400,000," points out Eric Newnham, managing director of specialist poster-buying company Poster Publicity. "The detailed position of every poster in the UK is carried on computer, so if you wanted to send a personal message to someone you could choose the poster on their way in to work, near their house, or wherever you wanted."
And that's not all: there are posters that smell, posters that play the radio, 3-D posters, posters that reveal different images depending on where you're looking at them, and posters that light up as you approach. The industry has moved on from the exquisite doodling of Toulouse Lautrec, Alphonse Mucha and Aubrey Beardsley to, for example, last year's poster for the film Striptease. This celebration of our own less genteel times actually showed Demi Moore undressing as you approached.
"The number of poster sites has actually fallen over the last few years, because the number of companies selling poster sites has contracted," explains Francis Goodwin, managing director at one of the UK's big five poster contractors, Maiden. "We've all invested in making the sites look more attractive. The result is that companies like De Beers and Estee Lauder, which wouldn't have used posters in the past, are now prepared to give it a go."
And for all that the number of sites declined slightly there's still plenty to choose from: more than 95,000 panels up and down the country, not counting the 418,000 sites available in the London Underground or on the sides of buses or taxis.
In the old days advertisers would own these sites all year - in fact Guinness kept a store of the same poster sites for 38 years from 1940- 1978; nowadays the typical campaign lasts for just two weeks. The controversial Benetton spots run for a single week, Eva Herzigova first beamed down at us all for a fortnight before she was pasted over. The urge to cut the clutter of all this ever-changing imagery is huge. But it has always been that way.
"The famous 'Careless Talk Costs Lives' campaign from 1940 has a red border," Timmers points out, "only because the artist Fougasse wanted, as he said, to stick out among the fruit salad of all the other ads: and it's the same today - nothing really changes."
Nothing, that is, except a bottom line which looks healthier by the year and which is starting to demonstrate, once and for all, the real power of posters.