While the rest of the UK will soon leave the European Union's single market, Northern Ireland will effectively remain within it for goods. From December 31 at 11 pm, all agri-food products arriving in Northern Ireland ports and airports from Great Britain will need to carry a Veterinary Export Heath Certificate. Given its position, Northern Ireland is supposed to be a bridge to the EU. But the new customs rules could create a large amount of paperwork. Meanwhile, products from Great Britain may become more expensive and more difficult to source. Our correspondent Hervé Amoric reports.