score:3
Part of this stems from Operation Gull, which is in place on a non-systematic basis at English airports as well as Northern Irish air- and seaports.
It is a measure to identify people intending to use the Common Travel Area (a British-Irish semi-open border concept) as a loophole to enter the republic of Ireland, as border controls at the land border are limited to spot checks on the motorway and trains between Belfast and Dublin.