The key question here is this: where did Abu Zakariya al-Britani learn his understanding of Islam? From anyone in Britain? If so, who? Are British authorities looking into this? Or are they waving away the question with the all-purpose dodge that Abu Zakariya al-Britani was “radicalized on the Internet”?

“British ISIS fighter carries out suicide bomb attack at military HQ outside Mosul as Iraqi forces move to reclaim the city,” by Dave Burke, Mailonline, February 20, 2017:

ISIS has claimed responsibility for a suicide bombing which it said was carried out by a British terrorist close to the Iraqi city of Mosul. The attack targeted a military facility to the southwest of the war-torn city, and the group claims it resulted in multiple casualties. ISIS named the bomber, who was driving an explosives laden vehicle, as Abu Zakariya al-Britani. A statement released by the terror group today said: ‘The martyrdom-seeking brother Abu Zakariya al-Britani – may Allah accept him – detonated his explosives-laden vehicle on a headquarters of the Rafidhi army and its militias in Tal Kisum village, southwest of Mosul.’ It did not reveal when the bombing took place. ‘Rafidha’ is a derogatory term used to refer to Shiite Muslims, who Islamic State fanatics consider to be heretics. Forces from the Hashed al-Shaabi (Popular Mobilisation), a paramilitary umbrella dominated by Shiite militias backed by Tehran, are active in the area mentioned in the statement….

“Rafidha” means rejectors, i.e., the Shia are rejectors of the first three caliphs, Abu Bakr, Umar, and Uthman. This is not something only “Islamic State fanatics” think; many Sunnis believe this.