An interesting article from the Independent:

"The EU has just passed a law that could end the problems with free movement which led to Brexit in the first place.

Corporations will no longer be able to undercut local workers by exploiting migrants. Looking beyond Brexit, this law will make a big difference regardless of the option chosen for our future relationship with the EU"

I am not sure how such a law will work in practice - there is a massive financial incentive for businesses to find ways round it. But at the very least it is an acknowledgement that it is something many people have been concerned about.