BA 349 then BA 394 at Heathrow
Nice → London → Brussels
Timetable, London time
21:05BA 349 from Nice at the gate
17:55BA 394 to Brussels leaves the gate
20 h 50 apart on the timetable, overnight
BA 394 leaves 20 h 50 after BA 349 arrives on the timetable: more than half a day, so not a connection we count.