Before the census of 2001, there was no way of accurately determining the size of the Muslim population in Britain, as previous censuses did not categorise religious affiliation. The best estimates, in 1991, concluded that the Muslim population at the time stood at one million, with 80% being of South Asian origin. The remainder were drawn mostly from the Arab world, Malaysia, Iran, Turkey, Cyprus, and East and West Africa (Lewis 2004: 14). With natural growth, continuing globalisation and post-colonial migration fuelled by economic hardship and conflict, more migrants arrived in Britain from other parts of the Muslim world. By the 2001 census, the Muslim population had risen to 1.5 million, now with some 65% of South Asian origin, indicating the increasing multi-ethnic make-up of Britain's Muslim population.

Although references to Muslims in Britain date back to the fifteenth century, the first settled communities emerged in the late nineteenth century. The country's first mosque was created not by Muslim migrants but by an English convert to Islam, Abdullah William Quilliam, who adapted a house in Liverpool into the first recorded mosque in 1887. In 1889, a Hungarian Jew had built the first purpose-built mosque in Woking, south of London (plate 20). There were then only two more built examples to follow before the Second World War, one in south London by the Ahmadiyya community in 1925 and the other in Cardiff in 1946.

Imperial Britain had over centuries established multiple political, cultural and social links with its colonies, where most of its subjects were Muslim. It was through these imperial projects that Muslim communities first settled in Britain, coming to the country, for example, as seamen, students and scholars. These early settled communities formed in the port areas of Cardiff, Liverpool, South Shields and East London. A series of mosques were established in converted houses, and one was built by the late 1940s by Yemeni sailors in Cardiff 's Tiger Bay. The Muslim community until the Second World War was mostly limited to port towns or was otherwise intellectuals, students, dignitaries or converts in and around London.