BA 349 then BA 1410 at Heathrow
Nice → London → Belfast City
Timetable, London time
21:05BA 349 from Nice at the gate
18:45BA 1410 to Belfast City leaves the gate
21 h 40 apart on the timetable, overnight
BA 1410 leaves 21 h 40 after BA 349 arrives on the timetable: more than half a day, so not a connection we count.