Cities are cosmopolitan by nature.
Also, immigration into London worked fine until recent years. The postwar immigration of blacks from the Caribbean, Indians, black Africans from countries like Kenya and even the original Muslim Pakistanis in the 50’s to 70’s worked fine. Hardworking, law abiding people.
It is the radicalised intake of the last 20 years, the idiocy of high immigration under Labour allied to the moronic policy of multiculturalism that has caused problems.