But as I noted above, the average UK citizen is not in favor of strict immigration controls (legal or otherwise) and certainly not supportive of the recent riots.
Of those who are, the majority comes from lower-income areas that suffered the most under years of Tory austerity, which is understandable. But even then it’s really a case of the socioeconomic elites pointing the finger at immigrants rather than themselves.
As for the Muslim community, again there is good evidence to suggest that a lot of the fears you mentioned are unfounded. Surveys have shown that most feel that they belong in Britain and have no objections to integrating with the culture.
Again, the problem you tend to find is that extremists like Anjem Choudary are amplified by the press, giving the impressions that the Muslim community is incompatible with British values, when in fact the vast majority disagree with that statement.
Aesthetics, plus the seductive appeal that pre-modern, pre-liberal-democratic societies (when the governments were authoritarian, the women were submissive, and the men “were men”) have for reactionaries, incels, and cryptofacists.