Penguin, pioneer of the paperback novel, is celebrating its 70th anniversary.
Defined by generations of iconic covers, Penguin publications adorn bookshelves across the globe, prompting a rush of nostalgic affection.
But what makes Penguin one of the world's most enduring publishers?
Contrary to popular belief, Penguin founder Allen Lane did not invent the paperback book, but he made it respectable.
Prior to 1935, when Mr Lane and his brothers Richard and John, gambled their own cash to publish 10 titles, paperbacks were synonymous with "pulp fiction", cheap novels typified by lurid covers and poor-quality writing.
Wyndham's The Day of the Triffids spawned a classic Penguin cover
A natural businessman, Mr Lane noticed a gap in the market for quality paperbacks while stranded at Exeter station with nothing to read.
It was his aim to make quality books as affordable as a packet of cigarettes - just sixpence - opening up the world of literature to those who had previously borrowed from the library.
The first 10 Penguin paperbacks were reprints of hardback books, among them Agatha Christie's The Mysterious Affair at Styles and Hemingway's Farewell to Arms.
Rights were sold by hardback publishers who did not believe Mr Lane would be able to pull off the enterprise.
It was certainly a gamble. To make a profit, Mr Lane had to sell 17,500 copies of each of the 10 books.
But after a slow start the project was rescued by a large order from Woolworths, and sales soared.
More than 150,000 copies were sold in the first four days and three million by the end of the year. A year on, it was estimated that that a Penguin book was bought every ten seconds.
And in 1937, the Penguincubator was born - vending machines on railway platforms - taking Mr Lane's idea back to its original birthplace.
Allen Lane understood that great ideas need great marketing, and it was Penguin's inspired branding that turned the company into a publishing tour-de-force.
The two-tone covers allowed the publisher to share equal space with the author and title, while the small penguin logo - sketched at London Zoo - underscored the company's pulling power.
Mr Lane considered illustrated book covers to be crass, and stole the idea of using colour-coded covers from an Anglo-German publisher called Albatross Verlag.
Readers quickly came to recognise genres by colour: orange for fiction, green for crime novels, blue for biography and so on.
But as the company evolved, so too did the covers.
In the 1960s they were defined by Italian art director Germano Facetti.
Facetti added a compelling image, be it a graphic illustration or a historic painting, to the tripartite covers, designed to echo the contents of the book.
Classic works like Miro's The Tilled Field adorned George Orwell's Animal Farm, while a Duffy landscape beckoned the reader to delve into EM Forster's Room With A View.
But JD Salinger's Catcher in the Rye had a blank cover because the author refused to condone any illustration.
The covers became increasingly commercial - and for many readers lost their iconic look.
Allen Lane abhorred the vulgar illustrations and branded the covers "breastsellers".
Penguin has established strong bonds with many of its authors over the course of its 70-year history.
Evelyn Waugh, Muriel Spark, Roald Dahl, Margaret Drabble, Nick Hornby and Zadie Smith are among their authors championed by the publishing house.
Lane died in 1970, nearly a decade after Penguin went public
Nowadays, there are some 5,000 different titles in print at any time, translated into up to 62 languages.
A champion of free speech, Penguin has defended many of its authors.
It published Salman Rushdie's The Satanic Verses in 1988 despite accusations of blasphemy against Islam, and the subsequent fatwa against Rushdie.
It also successfully defended a libel suit brought by revisionist historian David Irving in 2000 after the publication of Professor Deborah Lipstadt's Denying the Holocaust.
But the most famous legal battle took place in the 1960s when Penguin was prosecuted under the Obscene Publications Act over its decision to publish DH Lawrence's Lady Chatterley's Lover in full.
Penguin's acquittal marked a turning point in British censorship laws, and two million copies of Lawrence's scandalous novel were sold in six weeks.
From its humble beginnings in a church on London's Marylebone Road, Penguin had become a national institution.