Without checking the numbers or anything, I'm pretty sure the cost/benefit calculation of Brits going to China for jobs is a hell of a lot different from other big historical job-driven emigration waves (Irish to US, Italians to Argentina, Mexicans to US, Turks to Germany, the Great Migration of blacks within the US), before you even start to think about Chinese immigration policy.
Also, the problem ain't a structural new world order, it's a global downturn where you can't just pack up to where things are good, cause things are generally crap all over.
PS I only skimmed the initial post before, and didn't catch the part at how they calculate how many bedrooms you need for your kids. lolcry indeed