The UK is never going to crack down on illegal immigrants because they are an essential part of our economy. They do seasonal work picking flowers, hops, mushrooms, etc for a mere pittance that no citizen would accept. They work staggeringly long hours in restaurants for peanuts. They have no security whatsoever. For that reason, they do all the nasty stuff that we don't want to bother with. Consequently, unless we are prepared to accept massive price rises that would come if the jobs they did were actually state-approved and therefore subject to humanitarian controls, we are stuck with them.
The long term view is that these people eventually become discontented with their lot and before you know it we have another problem with yet another ethnic minority.
That's capitalism for you!
Englishman.