If we allow Britons to travel back and forth unchecked, we are asking for them to transport their problems here. They fouled their own nest. We don't need their troubles.
Open immigration was because of our ties to them. They must be severed, and quickly. Not encouraged! An analogy: It's like allowing a bunch of smallpox infected people to run amok among healthy people.
My feeling is that immigrants going there will be fed over to us by the UK government. Not a good idea. If you wish to come here, go through the process, otherwise, stay the hell out.
Don't worry. They don't want to stay here, anyway. They're all trying to make it to Gold Mountain, down south of us.