BA 42 then BA 418 at Heathrow
Cape Town → London → Luxembourg
Timetable, London time
06:40BA 42 from Cape Town at the gate
06:05BA 418 to Luxembourg leaves the gate
23 h 25 apart on the timetable, overnight
BA 418 leaves 23 h 25 after BA 42 arrives on the timetable: more than half a day, so not a connection we count.