Ireland could very well be a problem. As I understand it, Irish citizens have a right to come to the UK without restriction and have a right to vote in elections. In fact, they have a right to vote in the referendum election. I wonder if they will retain their historic rights.
The border between Ireland and Northern Ireland hasn't been addressed. Will this be a physical border? As Irish citizens can move freely to the UK anyway, will they be allowed to come and go as they please? Ireland isn't in Schengen at the moment, but it might well join in the future. Presumably there will have to be border controls to regulate non-Irish EU citizens.
It seems that this could become a very 'leaky' border.
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