evidence: "As it happens, the UK and Ireland are already very sparing in their checks on goods entering from outside the EU – only four per cent get checked by the UK and only one per cent by Ireland… "Only 5 per cent of Northern Ireland’s GDP goes to Ireland, and only 1.6 per cent of Irish exports go to Northern Ireland. There are only about 50 large companies that trade across the frontier" [...] Exports to the Republic of Ireland made up 33% of Northern Ireland’s goods exports in 2016—but only about 1.5% of the Republic’s goods exports went to the North that year. This trade was worth over £4 billion. Around 100 large Northern Irish companies made deliveries across the border that year (about 11% of all deliveries going from Northern Ireland to Ireland). [...] The Northern Ireland Statistics and Research Agency (NISRA) told us that around 100 "large businesses" (250+ employees) in Northern Ireland made deliveries across the border in 2016.