Animal and plant goods are the most affected by Brexit in the ports of Normandy, Philippe Deiss, managing director of Ports de Normandie, told Xinhua a day before Brexit.

According to previous arrangements, there is an 11-month transition period when Britons will trade freely with EU nations, after which controls will be put in place starting on Jan. 1, 2021, he said.

According to Deiss, storage and control spaces for goods have been built up by the ports of Normandy. They have also set up a computer system for exchanging data between importers, customs and carriers.

"Today, Brexit can be an opportunity," he noted. "We aim at the fluidity of circulation and if there is congestion in ports such as that of Dover in England which has huge activity each year, this can generate big traffic in secondary ports like ours, on the English and French sides."

Britain is the largest foreign market for wines from the Rhone Valley in France. In 2017, the region exported 160,000 hectoliters, or 17 percent of its exports, to the other side of the English Channel.

When Britain becomes a third country again, additional customs and tariff barriers may apply.

Francois Villard, a winemaker in Saint-Michel-sur-Rhone, said he did not know what would happen to the English market after Brexit. His company now employs 20 people and five percent of its production goes to Britain.

It is now impossible for him to predict pricing for his bottles after Brexit. Like most of the Rhone Valley winegrowers, he is now waiting to learn which customs regulations will apply.

Brexit, first scheduled for March 29, then postponed to April 12 and Oct. 31, finally took place on Jan. 31. More than three and a half years after the Brexit referendum, the consequences of the exit are still difficult to determine. A transition period will last until the end of 2020, and may be extended for up to two more years.