BA 591 then BA 484 at Heathrow
Venezia → London → Barcelona
Timetable, London time
13:10BA 591 from Venezia at the gate
12:55BA 484 to Barcelona leaves the gate
23 h 45 apart on the timetable, overnight
BA 484 leaves 23 h 45 after BA 591 arrives on the timetable: more than half a day, so not a connection we count.