BA 817 then BA 57 at Heathrow
Copenhagen → London → Johannesburg
Timetable, London time
22:35BA 817 from Copenhagen at the gate
21:15BA 57 to Johannesburg leaves the gate
22 h 40 apart on the timetable, overnight
BA 57 leaves 22 h 40 after BA 817 arrives on the timetable: more than half a day, so not a connection we count.