BeeDeeDubbleU - 10:50 am on Jul 23, 2013 (gmt 0)
It's more readily available and less easy to control on the Internet and bear in mind that no one is proposing a ban on p0rn.
You would have to look pretty hard to find material on the internet that is more capable of "corrupting innocence" (to use Cameron's words than some things available in bookshops (the works of the Marquis de Sade, for example).
But come one now, you are not seriously suggesting that bookshops are more of a threat to innocent kids than the Internet, are you? ;)