BA 871 then BA 406 at Heathrow
Budapest → London → Cairo
Timetable, London time
09:05BA 871 from Budapest at the gate
21:25BA 406 to Cairo leaves the gate
12 h 20 apart on the timetable
BA 406 leaves 12 h 20 after BA 871 arrives on the timetable: more than half a day, so not a connection we count.