FR 4855 then BA 553 at Fiumicino
Catania → Rome → London Heathrow
Timetable, Rome time
19:35FR 4855 from Catania at the gate
13:50BA 553 to London Heathrow leaves the gate
18 h 15 apart on the timetable, overnight
BA 553 leaves 18 h 15 after FR 4855 arrives on the timetable: more than half a day, so not a connection we count.