Muslim intellectuals may try to define something called British Islam, but the truth is that as the Muslim community of Britain has grown in size and religiosity, so too has the opportunity to found and run mosques which divide along ethnic and sectarian lines. Just as most churches in Britain are affiliated to one of the main Christian denominations, the vast majority of Britain's 1600 mosques are linked to wider sectarian networks: the Deobandi and Tablighi Jamaat movements with their origins in colonial India; the Salafi groups inspired by an austere form of Islam widely practiced in Saudi Arabia; the Islamist movements with links to religious political parties in the Middle East and South Asia; the Sufi movements that tend to emphasise spirituality rather than religious and political militancy; and the diverse Shi'ite sects which range from the orthodox disciples of Grand Ayatollah Sistani in Iraq to the Ismaili followers of the pragmatic and modernising Aga Khan. These affiliations are usually not apparent to outsiders, but inside Britain's Muslim communities sectarian divides are often fiercely guarded by religious leaders.