Erotic book beats Harry Potter to become UK best seller

The book "Fifty Shades of Grey," about a depraved relationship between a young female virgin and her rich older lover has become the fastest selling paperback since records began.

Erika Mitchell, who writes with the pen name 'EL James' beat JK Rowling and Da Vinci Code author Dan Brown in the UK records with the first instalment of her X-rated trilogy, the Daily Mail reported.

The first instalment of the X-rated trilogy, sold more than 100,000 paperback copies last week alone