Not all immigrants are good. Many cost society more than they contribute. The right kind of immigrants are good.
[0]https://www.dw.com/en/denmark-apologizes-for-abuse-of-people...
The point though - it's irrelevant. Even those cases, and even straight up cases where people come here and just go on the dole, don't change the fact that as a whole immigrants are a net positive to the country(financially), and that's based on the OFR findings not my imagination.
Myself I have spent almost two decades in Britain, paid my taxes (at the highest rate at that), and decided to leave when I saw that the immigration talk had turned everybody into racist lunatics, and even people like me, from the same continent, were made to feel unwelcome by this rhetoric. For all I care, it's a failed state, yet it has not yet seen the bottom until it progresses its descent into decay, the same that has infected the US and elected Trump.
You will get your Reform government and it'll be Brexit times 10. Only then, maybe, the British people will stop falling for far-right propaganda paid for the Russians.