Where does diversity stop and extremism begin? That, it seems to me, is the central question posed by the so-called "Trojan horse" affair.
It is official government policy to create a "more diverse school system" with academies and free schools liberated from some state controls. They don't have to follow the national curriculum and they operate independently from the local education authority.
A substantial proportion of the free schools created under Education Secretary Michael Gove's reforms appear to have a strong cultural or religious character.