W4 6723 then BA 635 at Athens
Venezia → Athens → London Heathrow
Timetable, Athens time
22:20W4 6723 from Venezia at the gate
16:45BA 635 to London Heathrow leaves the gate
18 h 25 apart on the timetable, overnight
BA 635 leaves 18 h 25 after W4 6723 arrives on the timetable: more than half a day, so not a connection we count.