Discussions are anticipated to be challenging with a raft of contentious issues including the free movement of people, trade and the so-called “exit bill” due from the U.K. to the EU.

The extremely thorny question of how to deal with a political border being reinserted between Northern Ireland – which will leave the EU along with the rest of the U.K. – and its Republican sister to the south is also expected to absorb a lot of time and energy.