QR 3692 then BA 483 at Barcelona
Rome → Barcelona → London Heathrow
Timetable, Barcelona time
17:05QR 3692 from Rome at the gate
15:30BA 483 to London Heathrow leaves the gatealso IB 3780, AY 5938, QR 5984, AA 7061, VY 9561
22 h 25 apart on the timetable, overnight
BA 483 leaves 22 h 25 after QR 3692 arrives on the timetable: more than half a day, so not a connection we count.