Does immigration affect the unemployment rate? If not, why should we be concerned?

I agree with what you have to say, all in all there is no logical reason to be concerned about immigration, despite what the racist far-right who merely wish to exploit the situation for political gain - it is, pure and simple racism.

You make a good point in how immigrants can effectively deplete workers' wages. This was the case during the mass immigration of the late nineteenth-century in the United States, which caused huge racial tensions and an antisemitic political movement subsequently. Some parallels can be drawn between late nineteenth century America and modern-day Britain; for one, a laissez-faire, classical liberal approach was applied in both cases - government was staunchly anti-Trade Union and workers' rights were next to nothing (the latter has not been as big a problem in recent years, though in the last year it has become a worsening issue). If, as you say workers had been unionised the whole situation in both cases could be wholly different.

I suppose one argument against unsustainable immigration (depending on how you want to define 'unsustainable') is the strain it puts on public services and housing. Demand for housing is only increasing whilst supply of low-price housing is stubbornly stagnant. Many would be angered by even greater house prices and greater competition on waiting lists to gain access to council housing.

But even as I say that, there are certainly non-xenophobic means that could tackle this; for one, government could repeal its 'right to buy' housing scheme, which seems to have only led to speculators exploiting the high demand in order to make larger profits while many are left without a home to live in. Government could involve itself in a housing scheme to provide affordable council housing for those without homes to reduce demand and waiting lists, whilst simultaneously renovating the countless derelict houses that go to waste across the United Kingdom. On private housing, Capital Gains Tax could be increased at the top threshold to 50% to sustain these housing schemes, instead of the ridiculously low tax-margings property developers currently face.

In short; government should actually take a role to tackle wage depression, public service sustainability and housing that can be caused by immigration under a free-market system - if the measures you and I have proposed do not work (which I think it would, or at least to a significant extent), then reducing levels of immigration should maybe be put into question.

You said yourself they are prepared to work for low wages. What on earth, as if I did not know, makes you think that keeping everyone's wages down is a good thing? Can't you see that the propaganda has sent you slightly mad. Do you want low wages?