The Tory proposal to cut immigration is to put a cap on skilled labour from outside the EU. There are soo many flaws in that proposal that it beggars belief.
1. The vast majority of immigration is from within the EU (both skilled and unskilled). The only way the UK government can stop that is by leaving the EU.
2. If someone from outside the EU marries a British citizen (or anyone from within the EU) they can migrate to the UK. There is no cap on this.
3. Legitimate refugees from war-torn countries or people who cannot return to their native country due to risk of mistreatment have to be allowed to stay in the UK by international law. I would assume the majority of immigrants who fall into this category would be unskilled.
4. That leaves the skilled labour from outside the EU. These are people who are predominantly very highly educated and who can make a valuable contribution to the economic output of the country. The kind of people who will have learnt how to speak English (or would have to learn as they would have to have a job offer to be able to go to the UK) and who would be more likely to integrate than some of the other categories above.
The whole point is that the Tories would have no effect on Solmalians etc as they are refugees. The question over whether they are legitimate or not is a valid one, but also very difficult to prove one way or another. As such it is very difficult to then deport them especially to a country that has no functioning government.
So why is Cameron making a big deal out of all of this if he is only putting a cap on a minority of immigrants and only on the immigrants who have the most to offer and the most likely to integrate into the wider community? Votes, plain and simple. He's playing the crowds who, after being whipped up to a frenzy by the right-wing media, are frustrated with Eastern Europeans, Kurds, Somalians etc... without telling them that his policy will have no effect on those immigrants because they are from the EU or are refugees. It's a very dangerous and devisive tactic where he is effectively saying immigration, and by extension immigrants, are bad.
Clegg actually had Cameron over these exact points in the leaders' debate last year... but since he has sold his soul for the glimpse of power, he's been mysteriously quiet on the issue.