QR 3737 then BA 495 at Barcelona
Nice → Barcelona → London Heathrow
Timetable, Barcelona time
23:05QR 3737 from Nice at the gate
20:45BA 495 to London Heathrow leaves the gatealso IB 3821, AA 6817, CX 7171, VY 9614
21 h 40 apart on the timetable, overnight
BA 495 leaves 21 h 40 after QR 3737 arrives on the timetable: more than half a day, so not a connection we count.