The Daily Mail is quick to point out that Fifty Shades of Grey has outpaced J.K. Rowling and Dan Brown, but it’s missing one crucial fact.

Yes, Fifty Shades of Grey has become the fastest selling paperback of all time, but the difference is that Grey premiered as a paperback, whereas most books premiere as hardbacks and therefore paperback sales are smaller.

From the report:

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.

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.’

Author E.L. James has recently been in Hollywood where she’s meeting with producers to jumpstart a book-to-film adaptation.