FR 6974 then BA 481 at Barcelona
Rome → Barcelona → London Heathrow
Timetable, Barcelona time
21:55FR 6974 from Rome at the gate
14:40BA 481 to London Heathrow leaves the gatealso IB 3663, AA 6819, VY 9559, QR 9800
16 h 45 apart on the timetable, overnight
BA 481 leaves 16 h 45 after FR 6974 arrives on the timetable: more than half a day, so not a connection we count.