Thing is, and it took me all too long to learn this, Schengen is not what enables foreign workers to enter another EU member nation. It just makes it easier.

The Brexit yes came overwhelmingly form the old industrial areas of UK. From the towns and such that has seen their quality of life stagnate or deteriorate while the jobs gets done by foreigners that come by the busload.

Damn it, i don't live in UK but i have seen the phenomena myself. A local wharf some years back had a boom year, and the the peak there were perhaps twice as many foreigners working there as locals.