U2 8244 then U2 831 at Gatwick
Thessaloniki → London → Belfast International
Timetable, London time
23:45U2 8244 from Thessaloniki at the gate
18:55U2 831 to Belfast International leaves the gate
19 h 10 apart on the timetable, overnight
U2 831 leaves 19 h 10 after U2 8244 arrives on the timetable: more than half a day, so not a connection we count.