No, not really. Broadly, immigration has no effect on crime-rates. In case-study after case-study, it’s shown immigration has little to no impact on crime-rates. This was even disproven after the height of the Syrian refuge crisis! But media likes sensationalist reporting, so public perception doesn’t match the statistics.
> cultural demise.
Meaningless, also created by the media. If you listen to the media, Britain is under the fierce grip of Sharia law, enforced by… the 6% of the population that is Muslim. Yes, yes, how scary. I guess English culture was pretty weak, to meet its demise from such a meager blip.