QR 3754 then BA 483 at Barcelona
Santander → Barcelona → London Heathrow
Timetable, Barcelona time
19:05QR 3754 from Santander at the gate
15:30BA 483 to London Heathrow leaves the gatealso IB 3780, AY 5938, QR 5984, AA 7061, VY 9561
20 h 25 apart on the timetable, overnight
BA 483 leaves 20 h 25 after QR 3754 arrives on the timetable: more than half a day, so not a connection we count.