What is needed is effective Border Control. I have no issue with legal immigration and anyone who can contribute to the Nation, irrespective of colour/religion is welcome IMHO.
What we do not need though, is a Border open to abuse from those who indulge in criminal activities, be it smuggling, trafficking or whatever.
Therefore, I would like to see a uniformed force (NOT the Armed Forces), controlled by the state, that is present 24/7 at every point of entry including small ports etc. Also, a beefed up Coastguard that can effectively police our territorial waters for the same purpose. More importantly, they will be employed to control entry, not fill in forms and compile statistics (like are useless Police Service).
It would not erradicate the problem but it would make a big dent in it.
Perhaps an immediate start would be to stop using the British Army to protect the Afghanistan Opium Crops.
Just a thought.