You could be sitting on a design classic

John Andrew discovers some obscure objects of desire

Investors are traditionally encouraged to pour their money into unit trusts, bonds and fund management companies, in return for which they regularly receive pieces of paper telling them by how much their savings have grown. For a minority of individuals, however, investing is as much an aesthetic question as a financial one.

Last month, Christie's of South Kensington opened its Europa Gallery with 5,000 square feet devoted to auctioning 20th century material. Today Bonhams, the pioneer of auctioning 20th century design, will be holding its ninth sale in London. Sotheby's has a similar event planned for 29 and 30 October.

What is offered in these sales and who are the buyers? Virtually anything - furniture, pottery and porcelain, glass, jewellery, sculpture, prints, paintings, lighting, TVs and stereos, textiles, office equipment and household gadgets and utensils. The buyers include museums, dealers, students of design and collectors, together with people wanting affordable "designer" furnishings for their home, plus increasing numbers who see the new market as a speculative punt.

At Christie's last month, objects placed under the hammer included Eero Aarnio's famous Ball chair of 1966, which was adopted as Number 2's chair in the cult 1960s TV series The Prisoner. Made from moulded polyester, it found a buyer at pounds 2,760, about 10 per cent up on prices secured for similar pieces at both Sotheby's and Christie's in April.

However, Vistosi glass birds designed by Allessandro Pianon, which Christie's were selling like hot cakes in April at pounds l,300-pounds l,500 each, were selling last month at pounds 800-pounds 900.

One catalogue for a Bonhams auction shows 1960s typewriters selling for around pounds 90. But hopes that such prices might be paid for a 1960s Imperial - the first electric portable typewriter to be marketed - are likely to be disappointed. It is Olivetti models that are sought, as these were styled by designers such as as Ettore Sottsass and Mario Bellini.

Likewise with furniture and lighting, it is not any old piece which is sought, but designer items that would have retailed at Liberty's, Heals and Habitat, as opposed to shops which sold purely functional productions made for mass sale. In other words, they were generally expensive at the time they were bought.

One of Christie's auctioneers, Mark Wilkinson, gave some clues as to what triggers demand. Two new books on Whitefriars glass and an exhibition at the Museum of London have resulted in a growing interest in the subject. Consequently prices have risen. "A year or so ago vases from the Whitefriars "Knobbly" range designed by William Wilson and Harry Dyer were selling for under pounds 20 a piece. Now the price is around pounds 50," Mr Wilkinson says.

Another example of an exhibition acting as a catalyst is the demand for Troika pottery. The work of a group of Cornish potters in the 1960s, it was a popular purchase by holidaymakers wanting a souvenir of the South- west of England. Until the exhibition, it would probably have been difficult to sell. Today, it realises good prices and demand is increasing.

Peter Hampson is a London silver dealer specialising in 20th century silver, including pieces from the 1960s. He points out that the market for most of the newer material is in its infancy. "Marketing by auction houses makes it fashionable to buy pieces from a certain era," he says. "In the early days prices can soar, only to settle at lower levels in the future."

His criteria for buying a particular piece are appropriate for any medium: "Initially it is a case of a little knowledge and gambling on your instinct. However, as my knowledge increases, my purchases become less of a gamble. I look for two things: style and workmanship.

"However, I will not buy something which is stylish but which is not well made. I only buy what I like."

What items dating back a few decades are worth keeping? Generally, quality traditional designs and stylish well-made contemporary pieces which capture the mood and spirit of the time.

Throwing out an Old Hall 1960s stainless tea service, a Braun table lighter or the piece of studio pottery you bought on holiday 20 years ago could therefore be a mistake.

Peter Hampson: 0171 229 8173

Bonhams: 0171 393 3970

Christie's: 0171 581 7611

Sotheby's: 0171 493 8080