Roll over psychedelia: the best-selling design at the exhibition of 'rock art', which opened at HMV this week, is Richard Hamilton's cover for the Beatles' White Album of 1968 - featureless except for the Beatles' embossed name and plate signatures.

The collection of 29 limited-edition lithographs of album covers, including 12 from the Beatles, was intended as a nostalgic celebration of the swirling psychedelia that briefly engulfed album design in 1967. But Britain's minimalist Beatle fans seem to have other ideas. A third of the 50 sold on the first day of the exhibition were of the Beatles' blank.

Published by the Pennsylvania company Musicom - founded by the author of the Beatles' history Ticket to Ride, Denny Somach - the lithographs are in big editions of 9,800. Although this country's ration is only 50 of each, their investment value is limited.

The exception is Brighton artist Roger Dean's 1974 design for Relayer, the cover that helped make famous the group Yes. His original watercolour and gouache image - snake, medieval horsemen, fantastic cliff castles - is being offered for dollars 650,000 (pounds 435,000) by a New York art gallery and even factory-made covers of his art on obscure labels like Vertigo can fetch pounds 600. No other album cover artist commands such prices. In the art market the value of originals influences the value of limited editions - something the Beatles minimalists seem to have missed.

As for Mariora Groschen, who posed nude aged 11 in 1969 for Blind Faith, she is still awaiting the horse that Eric Clapton promised her as a fee. All she got from Stigwood, his management organisation, was pounds 40.

Prices: Beatles pounds 135, pounds 175 framed, other designs pounds 99, pounds 150 framed. See exhibitions p11 for details

(Photograph omitted)