BA 1401 then BA 600 at Heathrow
Belfast City → London → Venezia
Timetable, London time
18:25BA 1401 from Belfast City at the gate
18:10BA 600 to Venezia leaves the gate
23 h 45 apart on the timetable, overnight
BA 600 leaves 23 h 45 after BA 1401 arrives on the timetable: more than half a day, so not a connection we count.