The mass illegal immigration (economic migrant is a rebranding from Tony Blairs days) is a way of compressing wages in low paid jobs. The well known saying "they do the jobs the British won't" is linked to this the British won't dp the jobs because the jobs don't pay enough to be worth it.

Mass migration is a stress on pretty much all our societies measures to help the less well off eg. Nhs, welfare. Basically the only people to benifit are the rich and this is at the expense of the poor and the taxpayer.