Fifty Shades Of Grey by E.L. James has become the number one best-selling Kindle book of all time at Amazon.co.uk, it was revealed today.

Despite the trilogy only being published in March this year, the racy international best-sellers have sold over one million copies in the online store’s Kindle department, while author E.L. James has become the bestselling author of the year on the site as a whole.

E.L. James, originally a self-published Kindle Direct Publishing Author saw popularity of her book soar online after readers embarrassed to be seen with a hard copy of the racy tome preferred to buy online.

The Kindle edition of Fifty Shades of Grey is currently outselling the print book at a rate of more than 2 to 1.

Fifty Shades Of Grey by E.L. James has become the number one best-selling Kindle book of all time at Amazon.co.uk

“E.L. James’ books have become both the fastest-selling and the best-selling series ever on Kindle. That’s an exceptional achievement for a debut novelist and we’re excited to see her pass the one million sales milestone,” said Gordon Willoughby, spokesman for Kindle.

“Following a stint of self-publishing, first online and then via KDP, E.L. James found a fan base and her success has rocketed from there.

“Her books have become a worldwide phenomenon demonstrating what a powerful launch pad KDP can be.”

In addition to the sales success seen on Kindle, Fifty Shades Of Grey, Fifty Shades Darker and Fifty Shades Freed are the first, second and third best-selling print books at Amazon.co.uk and their combined sales have also made her the best-selling print author of the year so far.

Sales of the book, the first in a trilogy, have overtaken the Harry Potter books and the Da Vinci Code, to the delight of not only E.L. James, but established romance writer Jilly Cooper.

Fifty Shades writer E.L. James, whose real name is Erika Mitchell has said she thinks her books are successful because they offer women a “holiday from their husbands”.