BA 719 then BA 512 at Heathrow
Zurich → London → Lisbon
Timetable, London time
19:15BA 719 from Zurich at the gate
18:55BA 512 to Lisbon leaves the gate
23 h 40 apart on the timetable, overnight
BA 512 leaves 23 h 40 after BA 719 arrives on the timetable: more than half a day, so not a connection we count.