It's pointless to deny that there's something going on here: EL James has now sold 4 million copies of her Fifty Shades of Grey trilogy via her UK publisher, Random House, to add to the 15 million that have been shifted in the US and Canada. In three months.
It's the fastest-selling book ever in both physical and ebook incarnations. In the UK alone, an extra print run of 2.75 million copies has been ordered. It's the fastest selling adult novel of all time. Which means it's the fastest-selling novel of all time that isn't Harry Potter.
The trilogy features Anastasia Steele, who falls in love with Christian Grey, a troubled young billionaire who likes sex only if he can accompany it with quite formal, stylised corporal punishment.
The narrative drivers are pretty slack - improbable dialogue ("I'm a very wealthy man, Miss Steele, and I have expensive and absorbing hobbies"); lame characterisation; irritating tics (a constant war between Steele's "subconscious", which is always fainting or putting on half-moon glasses, and her "inner goddess", who is forever pouting and stamping); and an internal monologue that goes like this … "Holy hell, he's hot!"; "No man has ever affected me the way Christian Grey has, and I cannot fathom why. Is it his looks? His civility? Wealth? Power?"
Its popularity has come as a bit of a surprise to publishers, who thought they knew what women wanted. People who like to trace all new trends back to new technology have offered this explanation - that women who wouldn't be seen dead reading smut on the tube could read it on their Kindle, and this launched a whole world of sales.
Fans were certainly quick to defend Dan Brown's The Da Vinci Code as it broke publishing records back in 2003, and Harry Potter addicts have been proud to wave a wand on behalf of JK Rowling's bestsellers since 1997. But what makes the triumph of James's book surprising is that a story involving such a succession of overtly kinky scenes can conquer the mainstream publishing market. After all, the plot is so single-mindedly titillating that it makes the unconventional "modern" relationships that leaven Stieg Larsson's Millennium Trilogy read like Charlotte Brontë in comparison.
James has managed to get millions of average readers to consider the place of erotic pain in a relationship without even advancing an argument or pretending to any literary merit. The book is "my midlife crisis writ large", Erika Leonard, the middle-aged British woman behind the pseudonym EL James, has recently admitted, adding that she put "all my fantasies in there".
Has James created the latest commercial genre for our age? Or does her racy trilogy answer a deeper, unmet need among women readers?
The feminist writer Marina Warner believes the unexpectedly wide appeal of this explicit fiction could be a sign of how difficult people now find it to feel aroused in an era when sex and nudity have become so commonplace. "There has been a general unveiling of the body in our culture and there is a connection between prohibition and arousal," she said.
Women writers have addressed extreme fantasies in the past, from Anne Desclos's Story of O (1954), to Fay Weldon's The Lives and Loves of a She-Devil and The Piano Teacher, by the Austrian Nobel laureate Elfriede Jelinek. In EL James's books the issues are handled more straightforwardly. When Christian introduces Anastasia to his "playroom" he warns her that she won't find an Xbox or PlayStation in there, but objects more closely associated with a medieval torture chamber.
Whether the Grey books are porn dressed up as romance, or romance dressed up as porn, remains up for debate. Whatever the answer, it is absolutely clear that for a while there will be nothing so good for flogging books as books about flogging.
Shades of Grey leads to adult hardware boom
The runaway success of Fifty Shades of Grey has led to a boom in adult toys and erotic literature. Ann Summers is just one of the stores reporting that sales of blindfolds, whips and handcuffs have soared, reflecting the strong sadism and masochism theme running through the book.
Punters, including many more women, are also lining up to buy more exotic sexual aids that feature in the love lives of the protagonists. Sales of jiggle balls, for example, have risen by 200%.
Fiona Davis, a director of Ann Summers, said the consumer effect of the book was similar to that of Sex and the City, which popularised designer shoes and vibrators.
"Fifty Shades of Grey has introduced erotic literature to millions of people who may have never considered exploring this genre," said Davis. Sales of other erotic literature has soared 130%.
In Soho, traditionally the centre of London's erotic entertainment industry, the sudden surge of interest is a welcome boost as the economic downturn continues. At Simply Pleasure, one of the district's most well-known adult bookshops, employees said that the curiosity generated by the book was introducing a new generation of women to sex shops and sex toys. "People realise that it's not seedy and sordid, which has always been the problem for the sex shop industry," said the store manager.