Collect to Invest: Italian design from the flower-power era turned convention upside-down. Now it's shaking London salerooms. John Windsor reports
Italian design is hot stuff. In 1968, while students and workers took to the streets in Paris, Berkeley and at the LSE in the cause of politics, Italians were rioting about design. They forced the 14th Milan Triennale exhibition to close after protesting that its designs were too mainstream.

Remember that next time you have the chance to sit in a Dorifora armchair designed by the maverick Italian Alchimia group. It mocks both over-elaborate traditional design and the constraints of modernism. Both a joke and a statement. A political statement, if you like. You can almost hear it talk.

In the late Seventies, Alchimia held gallery exhibitions that promoted design as art. They were a form of social/political subversion that has had no equal in this country. The nearest we have had to it is pop art - and punk.

Furniture, lamps, kitchen appliances and glass by turbulent Italian designers have become historical objects. Not just art history, but social and political history. This is why museums across the world are competing for examples, pushing up prices.

There has been a sudden deluge of Italian design in the London salerooms. Sotheby's and Bonhams held sales this month - with instructive results - and a sale containing the choicest, most iconic pieces is at Christie's South Kensington on 3 June (2pm). It is South Ken's first sale dedicated to Italian design.

Museums have been spending heavily because they fear that the Pesce Gaetano giant anglepoise lamp (1970-71) or the Cini Boerl "Serpentone" chair (1971) might be the last one they will get a chance to bid for.

This puts private buyers in a dilemma. Museums and rich collectors need only one example of each classic chair or lamp. Once they have bought one, they will not bid again. Demand then loses its edge. But who can tell when that is about to happen? A track record of auction values will have been established, and estimates will remain at deceptively optimistic levels.

You have to gamble. By refusing to engage in a saleroom duel, you might miss the last Gruppo Dam books-shaped "Libro" chair (1970). On the other hand, you might find that, soon afterwards, one more is tempted into auction by the high prices, just as competitive bidding is tailing off. There is one in the forthcoming South Ken sale estimated pounds 2,000-pounds 2,500. An incomplete one in Sotheby's sale last week was unsold at an estimated pounds 1,000-pounds 1,500.

Now is a good time to try your luck at auction because the May design sales have been hard on the pockets of museums and collectors alike. There have been record prices this month at Los Angeles Modern Auctions, the Treadway Gallery in New York, Sotheby's Chicago and Christie's Los Angeles.

This, coupled with the got-one-already syndrome, might explain the mixed reception given at London auctions recently to examples of a genuine rarity: the upholstered tubular steel Gruppo G14 "Fiocco" lounge chair (1970). Or is it because no one can sit for more than two minutes on the arty, sculptural thing without back strain?

One at Bonhams on Wednesday, estimated pounds 1,200-pounds 1,400 and missing a part, failed to find a buyer. Of two at Sotheby's last week, both estimated pounds 1,500-pounds 1,800, one fetched pounds 1,725, the other was unsold. But last March Christie's South Ken got pounds 2,070 for one. Demand seems to be wavering, but the chair is still a classic. Will anybody bid the estimated pounds 1,500- pounds 2,000 for South Ken's example? How many more are likely to come to auction? How many were made, anyway? That's the thing with Italian design. No one really knows. An educated guess says there were around 200 Fioccos.

Other classics on offer at South Ken: the scrumptious Gruppo Strum design group's "Pratone" (meadow) chair - if you can call it a chair. It is a piece of pop art, a mat with giant polyurethane spikes resembling blades of grass. Its anti-design message is: bring the outside in - let radical design groups infiltrate society. One was unsold at pounds 3,500 at Sotheby's last year. South Ken's is a 1986 re-edition estimated pounds 2,500-pounds 3,500.

As for the classic, and classical, "Capitello", by Studio 65 (1971), that tilts at Roman architecture and is tilted in a way that makes it unsittable on: one was unsold, estimated pounds 2,200-pounds 2,800, at Bonhams two years ago. British collectors were not as clued up then as now. A year later, one sold for pounds 2,530 at South Ken. Another on 3 June is estimated pounds 2,000-pounds 2,500.

Go for classic chairs and lighting - show-off objects for the sitting- room not the kitchen. Bonhams' undistinguished Italian tubular steel folding chairs and lamps were unwanted. In the same sale Ettore Sottsass's Vedic-inspired "Yantra" vases were popular at around pounds 500. But two-dimensional works stuck - even acrylics and gouaches by Alessandro Guerriero.

Star turn at Christie's South Ken on 3 June will be the first appearance at auction in London of the Archizoom group's pop art "Safari" six-seater sofa, designed with upholstered imitation leopard skin in 1968. Did Archizoom really mean to impose social intercourse on six people by seating them in a circle? Or is it a comment on social regimentation? To try it out at home will cost you pounds 8,000-pounds 12,000. But watch out - some well-brought- up museum curator with tidy habits might have taken a fancy to it.

Christie's South Kensington, 85 Old Brompton Road, London SW7 (0171- 581 7611).