BA 633 then BA 818 at Heathrow
Athens → London → Copenhagen
Timetable, London time
18:55BA 633 from Athens at the gate
18:45BA 818 to Copenhagen leaves the gate
23 h 50 apart on the timetable, overnight
BA 818 leaves 23 h 50 after BA 633 arrives on the timetable: more than half a day, so not a connection we count.