The albums you can judge by their cover thanks to Storm Thorgerson - the master of the record sleeve

He never played a note, but Storm Thorgerson left an indelible mark on the musical history of the 1970s. David Hepworth pays tribute

The cover of the 12in long-playing album had the magical effect of making the record within the cover seem more important than it was.

It's this canvas, longingly gazed at through the window of the Spinning Disc, sported beneath the arm of the party-bound sixth former or twirled between the listless fingers of a long hair perched equidistant between his new Wharfedales, which provided the visual focus for an auditory experience and encouraged a surprising wave of visual literacy.

Generations of people who knew nothing about art nonetheless knew that Peter Blake designed Sgt Pepper, that Andy Warhol provided the banana on the first Velvet Underground LP, that Robert Frank's photographs adorn the Rolling Stones Exile On Main Street and that the painting on the cover of New Order's Power, Corruption & Lies is A Basket Of Roses by Henri Fantin-Latour.

Storm Thorgerson, either as a member of the design group Hipgnosis or in his own right, designed covers that made explicit the sensory re-ordering which was at the heart of so many of the rock records that came out of Britain in the early 70s.

The highest accolade any album could have in those far-off, fold-out days was the description "really weird". The music could often be dismayingly orthodox but the packaging encouraged you to give it the benefit of the doubt when it came to artiness.

Heads took on the shape of giant thumbs for the unlamented Toe Fat, vast lightbulbs sat on polished ballroom floors to announce the arrival of the Electric Light Orchestra and eventually, most famously, an inflatable pig hovered over London's Battersea Power Station to herald Pink Floyd's Animals.

His creations eventually sat in the mainstream but they all began as hippy wheezes. The scions of Summerhill School and pranksters of the underground press found themselves with endlessly patient patrons such as Pink Floyd and the budgets it took to realise their visions.

Nowhere else would they have anything like the freedom. These bands didn't want their own faces on the covers and indulgent, frightened record companies would even let them get away with not including the title of the album on the outside.

Two of Thorgerson's most famous covers, Pink Floyd's Ummagumma and Atom Heart Mother, offered no more clue to their contents than could be provided by the pastiche of a Dutch master in the first case and a cow in the other. His best known work for them, The Dark Side of The Moon, had to carry a sticker announcing its name. Bands in those days seemed to think the only fans worth having were the ones prepared to hunt them out.

Both designers and acts seemed to revel in confusion. Thorgerson designed the first three Peter Gabriel albums, each of which was called Peter Gabriel.

Thorgerson preferred photography to illustration because it looked real. Since these were the days before Photoshop there was only one way to realise his vision of beds as far as the eye could see for A Momentary Lapse of Reason and that was by taking 700 hospital beds down to a Devon beach.

It rained and the exercise had to be repeated. When Hipgnosis were shooting Led Zeppelin's Houses of the Holy they had to spend 10 days on The Giant's Causeway trying to get the right images of naked children.

The amazing thing about this cover, which came out only a few years after Blind Faith had featured a naked pubescent girl, is that nobody considered it lewd or lascivious. By the time Thorgerson did the Scorpions' Animal Magnetism in 1989 people were easier to offend.

Everything in rock becomes heritage and unsurprisingly his skills were eventually sought out by latter-day prog rockers such as Muse for their Black Holes and Revelations.

But you can't put a great cover on a CD. The format repels mystique. All the really great rock records first appeared in a 12in cover. Storm Thorgerson got to express himself on quite a few of them.