You can't put a good bird down

Penguin is 70. Like many good inventions and many of today's older generation, the publishing phenomenon seems simultaneously older and younger than its true age. Older because it is hard to imagine bibliographic life before the convenience and accessibility of its paperback format, or to picture a domestic bookshelf without some of its familiar colour-coded spines. Younger because as a brand it has moved successfully with the times, managing to remain contemporary to each generation.

The birthday celebrations include a small exhibition at the Victoria and Albert Museum (running until November 13) that, together with Phil Baines's associated book, charts the evolution of the design and typography of the company's book covers since the appearance of the first Penguin, Andre Maurois's Ariel , on July 30, 1935. The first Penguins - brainchild of Allen Lane, the young managing director of the Bodley Head - were an immediate commercial success, quickly selling out their initial print runs, with Woolworths alone ordering more than 60,000 copies.

In Britain, Penguin and paperback have become virtually synonymous terms, but they were not the first portable, paper-covered literary texts to be marketed in this country. The Home and Colonial series produced by John Murray, a precursor of the World's Classics, first appeared almost a century earlier. And Lane's pioneering idea would have had a distinctly familiar ring to rival publishing entrepreneur John Holroyd-Reece, who launched his Albatross series in 1932. This featured classic and literary works produced in a pocket-friendly form; characteristically clear, simple typography and cover designs, colour coded for different genres; and all branded with a line-drawn logo of a bird (albeit an unfortunately doom-laden ornithological choice).

If Penguins were not quite the first, they quickly grew to be the best mass-market paperbacks in the country, gaining their reputation by combining a sound selection of texts with a careful control of costs that allowed them to remain readily affordable: the early marketing made much of the fact that the original cover price of 6d was equivalent to the cost of ten cigarettes.

But a big part of their success must be attributed to a wily recognition that the book-buying public would increasingly judge a book by its cover.

The initial, memorably simple design concentrated on establishing a reliably unifying image for the publishing house rather than promoting the individual title. It was the work of a 21-year-old office junior, Edward Young, and it included the stylised penguin logo - sketched from life by Young at London Zoo - in the lower of two coloured bands (orange for general fiction, green for crime fiction and blue for biography), with the author and title printed simply in black on the white central band in Eric Gill's sans serif typeface. Within six months of the launch, Penguin's identity could survive without reference to its respected parent, and the name Bodley Head was dropped from the covers.

In addition to a series of eye-catching composite tableaux of some 500 covers from the following 70 years, the displays at the V&A have drawn on previously unexhibited material from Penguin's archives at Harmondsworth, including original artwork and rough sketches that are particularly fascinating on the evolution of the logo: the penguin becoming notably more skittish during the war years. Baines's book, while not a comprehensive catalogue of Penguin's output, is itself a handsomely designed volume, reproducing nearly 600 cover designs that together illustrate not only Penguin's role in reflecting and influencing the changing fashions and preoccupations of British literary culture through the 20th century, but also chart the development of professional graphic design in this country.

Designers are rarely seen as the heroes of publishing histories, but Baines offers biographical thumbnails of all Penguin's key designers. It is refreshing to have them centre stage and to be able to put faces to the typefaces. Following Young, whose own war memoir One of Our Submarines became Penguin number 1,000 in 1954, came two exiles from Nazi Germany, Jan Tschichold and Hans Schmoller. Their reforms to Young's original horizontal grid design were subtle, but applied a characteristically rigorous consistency across the full range of publications. In the late 1950s, Abram Games, celebrated as the designer of the emblem of the Festival of Britain, ventured more radical change with the introduction of colour illustrated covers. His experiment proved short lived when Allen Lane balked at the expense; but colour would come, and indeed photographs, in the term of the Italian Germano Facetti as art director in the 1960s.

Baines's compilation of cover designs lays claim to being the largest from a single publisher ever reproduced in one volume. Scanning this archive of images, the best designs, such as the menacing and iconic cover for Anthony Burgess's A Clockwork Orange , stand out as defiantly and definitively of their time; others, such as the soft-focus 1970s version of The Great Gatsby , featuring Robert Redford and Mia Farrow, merely seem dated. But the cumulative whole reveals that the story of Penguin covers is about far more than "three coloured stripes and a dancing bird".

Christopher Phipps is head of reader services, London Library.