When did you last buy a Cornetto? Recently? Never? Walls sold 70 million of them last year. But there's something old-fashioned about the Cornetto now. The conical cardboard wrapper, the curly Italianate typeface, the same Walls logo that you see on pork sausages. This isn't how ice cream is marketed any more.

Take the flavours: for "Choc'n' Nut" read "Rainforest Crunch" or "Chocolate Fudge Pecan". Then again, it's hard to imagine the Haagen Dazs couple getting so animated over something designed to prevent you from having to lick the drips off your fingers. Unless Madonna can be persuaded to attach a pair of Cornetti to one of her Gaultier corsets, it's hard to see how this veteran of the adult-oriented ice-cream market could harness the selling power of sex.

The old ice age

But the world was different back in 1976, when Walls borrowed the Cornetto from an Italian company, also owned by Unilever, and launched it on a UK market where ice cream generally came swirled on top of brittle orange cones, or sandwiched between wafers. The ice-cream market then was based on the assumption that most of its consumers were children. Adults, it was thought, would not make a habit of eating ice cream in public. This notion was about to be overturned.

As ice cream, it was unremarkable: milk, cream, butter and sugar, but not necessarily in that order, whipped with a relatively large amount of air, compared to today's dense, luxury lines. The gimmick lay in the fact that it was the first ready-made ice cream delivered to the shops wrapped and ready to go. This had several advantages. For the person eating it, clean fingers and ice cream all the way down. For the person selling it, no need for machines, scoops or beer-pump handles. Less mess, less time, less perishability. All you needed was a chest freezer. And as it happened, Walls were (and are) willing to lend these to retailers on condition they only stocked Walls ices.

Twenty years ago, when the advertising agency Still Price Lintas cast about for an image that summed up the idea of a specifically adult treat, they came up with Venice, represented in a long-running series of television advertisements by the now famous tenor gondolier. One measure of this campaign's success is that old-timers still sing Just One Cornetto instead of O Sole Mio. Another is the fact that the idea it set out to debunk - that there is something silly about adults eating ice cream - seems very remote.

Oh tempora! Oh magnum!

Today, about half of all "impulse" ice-cream products (as distinct from take-home-in-tubs kind) are aimed at adults, and the market is worth pounds 289 million a year. The Cornetto has been displaced as the top seller by the Magnum, a chocolate-coated hunk in a gold foil bag (advertising slogan "Me and my Magnum": O tempora, O mores). Its territory has been invaded by frozen versions of familiar chocolate bars, starting with the frozen Mars six years ago.

Can it compete? Over the years, Walls have made the Cornetto creamier, but they have no plans to relaunch it. They do, though, have their eyes on another untapped market. Unilever have built three factories in China. One makes Omo, the others - just one billion Cornettos