'Mummy porn' Fifty Shades Of Grey outstrips Harry Potter to become fastest selling paperback of all time

She describes her books as ‘romantic fantasy’ stories, which offer women a ‘holiday from their husbands’.

And it seems millions are taking EL James at her word – with her explicit novel Fifty Shades of Grey now the fastest selling paperback since records began.

The novel, the first instalment of an X-rated trilogy, has beaten JK Rowling and Da Vinci Code author Dan Brown to the UK record.

Sensation: English mother-of-two Erika Mitchell, 49, wrote the best-selling book under the pen name E L James

At first, most sales of The Fifty Shades series, about a depraved relationship between a young female virgin and her rich older lover, were of the more discreet ebook version.

But, as the trilogy’s popularity has soared, physical book sales have taken off.

Last week alone, the first instalment sold more than 100,000 paperback copies – a feat most of the Harry Potter books and all of the Twilight novels failed to achieve.

Fifty Shades of Grey has been Britain’s best-selling book for nine weeks, while the trilogy has held the top three spots on the UK paperback book chart for the past six weeks.

Experts say the success of the racy books – dubbed ‘mummy porn’ – has been driven by frustrated middle-aged mothers.

A hit: Fifty Shades of Grey by E L James

Philip Stone, who compiles book charts for The Bookseller magazine, said their reputation had been spread ‘totally through word of mouth’.

He said: ‘It is highly unusual for a book to sell so well without there being a film adaptation or the author being well known, like Dan Brown or JK Rowling.



‘Clearly it has become acceptable for something like this to be talked about openly.’

A spokesman for Nielsen Book-Scan, which compiles the official chart figures, added: ‘The success has not been driven by people who regularly buy books, but by people who buy maybe three or four books a year.

‘The books have crossed into the mass market. Clearly, people aren’t embarrassed by it any more.’

The Fifty Shades trilogy tells of the sexual awakening of university student Anastasia Steele and her relationship with handsome billionaire Christian Grey.

While there are a number of graphic sex scenes, some involving sado-masochism, it is centred on a conventional love story.

The books were written by English mother-of-two Erika Mitchell, 49, using the pen name EL James. She initially posted the tales on the internet as fan fiction based on the Twilight books.

Two years later, she is said to be worth almost £4million after signing book deals on both sides of the Atlantic and a Hollywood movie contract a few months ago.

And Mrs Mitchell, who has been married to scriptwriter Niall Leonard for 25 years, claims fans have written to thank her for spicing up their marriages with the books.

Charlotte Bush, director of publicity for Arrow, which publishes the book in the UK, said: ‘The sales are incredible.'