BA 583 then BA 868 at Heathrow
Milan → London → Budapest
Timetable, London time
13:30BA 583 from Milan at the gate
13:00BA 868 to Budapest leaves the gate
23 h 30 apart on the timetable, overnight
BA 868 leaves 23 h 30 after BA 583 arrives on the timetable: more than half a day, so not a connection we count.