You're right, but this is not the EU Directive on free movement, but the agreement on Internal Borders...
The Schengen Area is the area comprising 26 European countries that have abolished passport and any other type of border control at their common borders, also referred to as internal...
In all seriousness... the Hadrian's Wall aspect could prove to be very significant (although the wall is far too far south! We need something actually at the border!).
Scotland will have to apply to be in the EU (which they will be fast-tracked into) then, like all new entrants, they will have...