The TUC have published a detailed report on the impact of migrant workers:
Contrary to far right accusations that immigrants are a drain on the welfare state, TUC research shows that migrant workers are paying more in taxes than the value of the public services they receive. Across the economy the arrival of migrant workers has not depressed jobs or wages, and although there is limited evidence of some local effect on wages and employment for low-skilled workers, so far low-skilled workers have not lost out thanks to the vibrant economy.
To continue with that good performance we need to ensure unscrupulous employers stop taking advantage of migrant workers' lack of knowledge of their rights and poor English, the report says. The solution is to crack down on the minority of bad employers by properly enforcing employment rights such as the minimum wage and closing loopholes such as the poor protection enjoyed by agency workers, not by taking it out on the migrant workers suffering the exploitation.
The report is to be welcomed. I have often heard the far-right criticising migrant workers. It is good to have some research to balance the debate. One thing I often hear is that migrant workers are working for less than the minimum wage. As the TUC quite rightly points out, that is the fault of unscrupulous employers, not the workers.