FR 4855 then BA 551 at Fiumicino
Catania → Rome → London Heathrow
Timetable, Rome time
19:35FR 4855 from Catania at the gate
12:10BA 551 to London Heathrow leaves the gate
16 h 35 apart on the timetable, overnight
BA 551 leaves 16 h 35 after FR 4855 arrives on the timetable: more than half a day, so not a connection we count.