BA 349 then BA 736 at Heathrow
Nice → London → Geneva
Timetable, London time
21:05BA 349 from Nice at the gate
12:40BA 736 to Geneva leaves the gate
15 h 35 apart on the timetable, overnight
BA 736 leaves 15 h 35 after BA 349 arrives on the timetable: more than half a day, so not a connection we count.