BA 349 then BA 137 at Heathrow
Nice → London → New Delhi
Timetable, London time
21:05BA 349 from Nice at the gate
15:05BA 137 to New Delhi leaves the gate
18 h apart on the timetable, overnight
BA 137 leaves 18 h after BA 349 arrives on the timetable: more than half a day, so not a connection we count.