BA 879 then BA 406 at Heathrow
Bucharest → London → Cairo
Timetable, London time
09:05BA 879 from Bucharest 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 879 arrives on the timetable: more than half a day, so not a connection we count.