BA 399 then BA 580 at Heathrow
Cairo → London → Milan
Timetable, London time
09:05BA 399 from Cairo at the gate
08:15BA 580 to Milan leaves the gate
23 h 10 apart on the timetable, overnight
BA 580 leaves 23 h 10 after BA 399 arrives on the timetable: more than half a day, so not a connection we count.