BA 349 then BA 826 at Heathrow
Nice → London → Dublin
Timetable, London time
21:05BA 349 from Nice at the gate
12:45BA 826 to Dublin leaves the gate
15 h 40 apart on the timetable, overnight
BA 826 leaves 15 h 40 after BA 349 arrives on the timetable: more than half a day, so not a connection we count.