BA 349 then BA 496 at Heathrow
Nice → London → Barcelona
Timetable, London time
21:05BA 349 from Nice at the gate
19:15BA 496 to Barcelona leaves the gate
22 h 10 apart on the timetable, overnight
BA 496 leaves 22 h 10 after BA 349 arrives on the timetable: more than half a day, so not a connection we count.