summary of article:D

Only poles need apply: Factor that 'bars Britons' highlights growing market in cheap migrant labour.

The article is about mystifying situation created on English labor-market, which causes unfair competition amongst the workers.
The most progress reduction of the English workers provided the most known and the biggest company Forza AW, which officially prefer employ polish workers because of all health and safety training is carried out in Polish.
The unofficial aspect is odder than this above, companies in England prefer more to employ the Polish emigrants due to lower needs of worker conditions. The advantage of Polish workers is that they can receive lower payment, they can agree on worse treatment.
But companies do not stop, they start provide more strict recruitment. On the advertisements to work temporary appears sentences like 'Only Polish', 'Polish required'. Hundreds of English workers have been laid off instead of Polish.