Pakistan has a history of tribalism. Violence (gang rape especially of girls and boys) is not only aimed at people of different cultures and religions but at people from rival villages of whom are of the same ethnicity and religion. So one could say this has not much to do with Islam.
Lets not forget the fact that Mohomed himself had sex slaves and had a 9 year old wife. Add to it that England is forcefully occupying (with NATO forces) Iraq and Afghanistan (Islam majority countries) they (the culprits) probably considered these girls as women of their enemies and did what their messenger would have done.
An act of revenge committed inline with what their holy messenger would have done under similar circumstances.