Nigel doesn't know what he's talking about.
The current immigration legislation limits the number of Tier 2 (general workers as opposed to students, sportsmen, religious leaders and high value migrants) to those with the sponsorship of a UK company. The Immigration Service writes:
"The job on offer must be one that cannot be filled by a worker already resident in the UK. Since 2011, there has been a cap of 20,700 visas that can be issue in this category every year"
There is also a category of temporary worker permits and you can debate whether or not benefits are a disincentive for Brits to do those low paid jobs, but there aren't that many migrants who come in on the general worker tier permit.
If there is a problem with foreigners working illegally that can be resolved by simply implementing the law - the existing law.
The real issue for me is one of perception. UKIP voters I've spoken with seem to think that foreign workers are a huge problem which they aren't. Then I discovered that the guys I was talking with thought that "British Asians" and "Black British" people are actually foreigners so I guess that explains it.