The two main political parties in Northern Ireland announced a deal last month to restore the region’s power-sharing government, which had ceased to function three years ago.

One of the main attractions at the local museum in Newry, a bustling market town some 40 miles south of Belfast, is an old wooden sign.

Britain’s impending departure from the European Union on Jan. 31 is merely, as Winston Churchill might have said, the end of the beginning.