In short, the PM is making it a crime to have certain, warped sexual fantasies, to get excited, in your head, by things that the vast majority of us find disgusting. He's making the enjoyment of certain fantasy images and fantasy words into a thoughtcrime.
About David Cameron
David Cameron took office in 2010 after forming a coalition government with Nick Clegg. He has since seen the popularity of his party fall as well as internal rebellions against the alliance with the Lib Dems.