FR 6927 then BA 555 at Fiumicino
Barcelona → Rome → London Heathrow
Timetable, Rome time
17:55FR 6927 from Barcelona at the gate
15:55BA 555 to London Heathrow leaves the gate
22 h apart on the timetable, overnight
BA 555 leaves 22 h after FR 6927 arrives on the timetable: more than half a day, so not a connection we count.