QR 3692 then BA 475 at Barcelona
Rome → Barcelona → London Heathrow
Timetable, Barcelona time
17:05QR 3692 from Rome at the gate
11:40BA 475 to London Heathrow leaves the gatealso IB 3658, LA 5488, AA 6814, VY 9640
18 h 35 apart on the timetable, overnight
BA 475 leaves 18 h 35 after QR 3692 arrives on the timetable: more than half a day, so not a connection we count.