BA 345 then BA 600 at Heathrow
Nice → London → Venezia
Timetable, London time
17:15BA 345 from Nice at the gate
17:00BA 600 to Venezia leaves the gate
23 h 45 apart on the timetable, overnight
BA 600 leaves 23 h 45 after BA 345 arrives on the timetable: more than half a day, so not a connection we count.