In two of Northern Ireland’s port towns, the starkly different economic impacts of the 10 years since Brexit come to life. In Larne, garden centre owner John Shannon points to a £387 “export charge” he must now pay just to bring in roses from Great Britain (GB). In Warrenpoint, food manufacturer Brian Reid sees a different reality. “Off the back of the Brexit vote, we picked up a lot of customers who wanted to source on the island of Ireland,” h…