It could be they weren't bricklayers but were in fact doctors in need of a language course.I had a couple of Polish ‘brickies’ on-site for a very short period. A 5 year old child could have laid blocks better, they were useless. This is not to say they are all useless just the ones I unfortunately met a few months ago.
There is a system currently being operated in the UK for companies to justify employing non UK / EU staff. This will be simply extended to cover future EU applicants.