Perhaps this video will give you a clue as to why Britain continues to be subject to home-grown terror attacks, watch and listen closely.
Here’s the Wikipedia entry for Dar al Harb:
Dar al-Islam (Arabic: ??? ??????? literally house of submission) is a term used to refer to those lands under Muslim government(s). In the conservative tradition of Islam the world is divided into two components: dar al-Islam, the house of peace and dar al-Harb, the house of war.
Dar al-Islam and its associated terms are not found in the two most basic works of Islam, the Qur’an and the Hadith. Some modern Muslim scholars maintain that the labeling of a country or place as dar al-Islam or dar al-harb revolves around the question of religious security. This means that if a Muslim practices Islam freely in his place of abode, then he will be considered as living in a dar al-Islam, even if he happens to live in a secular or non-Islamic country. Traditional definitions tend to focus on which religion holds ultimate authority.
Recently, some Western Muslims have challenged the dar al-Islam/dar al-Harb worldview, suggesting additional ‘houses’ (or ‘abodes’) to describe differing situations. These have been criticised as being in violation of Islamic law and definitions by others
