Pretty much all immigrants are good, or at least good for something. People generally want or need all the same things. Xenophobia by and large is an irrational urge.
I am sure that Denmark, a country that amongst other things imposed forced sterilisation against the Inuit population up until the 1970s, and abused people with disabilities [0], is offering black-skinned people equal opportunities and not pigeon-holing them into unemployment and social exclusion...
I mean, it's not particularly difficult to imagine(and I'm an immigrant to the UK). You move here, then after a while you bring over your retired parents to care for them in their old age. They are not contributing financially to the system but they are costing British taxpayers a lot of money.
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.
Brexit was about leaving Europe, whose immigrants where overwhelmingly young people or couples which would've been net contributors, spending up to a decade before returning to their home countries. I have literally seen this happen dozen of times in my time there.
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.
Mixing of cultures always lead to adding up their different solutions to all kinds of problems, improving the fitness of the result among other groups of humans.
It's gathering all the positive ideas or traditions of several groups, and the less useful or negative aspects tend to just fade naturally.
Migration is not just a choice between an open door and a closed door, but a spectrum. There are a variety of levels between those two extremes.