BA 571 then BA 510 at Heathrow
Milan Linate → London → Lisbon
Timetable, London time
15:15BA 571 from Milan Linate at the gate
14:50BA 510 to Lisbon leaves the gate
23 h 35 apart on the timetable, overnight
BA 510 leaves 23 h 35 after BA 571 arrives on the timetable: more than half a day, so not a connection we count.