Britain's European Union envoy has arrived at his office in Brussels for a meeting, hours ahead of triggering Brexit. Barrow will later take a break from the meeting and hand-deliver a letter signed by Prime Minister Theresa May at around 1130 GMT (7:30 a.m. EDT) to EU Council President Donald Tusk. Britain is set to formally file for divorce from the European Union, ending a 44-year relationship following the decision made by U.K.