European Union (Withdrawal) Bill

My Lords, I have noticed that the discussions have concentrated on trade, and I understand the good reasons for that. However, the matter that I raised concerns the movement of people. The noble Lord, Lord Empey, is very knowledgeable about Northern Ireland and the south and so forth, so I would like to ask him how you deal with the fact that the Republic will remain part of the European Union and have free movement of people, whereas the north will not if we leave completely and are not part of the single market. How do you deal with that in the context of immigration policy? Technology cannot deal with this. Where will people’s documents be examined to see whether they have an entitlement to make the passage? Where will that happen?