BA 349 then BA 466 at Heathrow
Nice → London → Madrid
Timetable, London time
21:05BA 349 from Nice at the gate
15:00BA 466 to Madrid leaves the gate
17 h 55 apart on the timetable, overnight
BA 466 leaves 17 h 55 after BA 349 arrives on the timetable: more than half a day, so not a connection we count.