GQ 841 then BA 635 at Athens
Vienna → Athens → London Heathrow
Timetable, Athens time
21:55GQ 841 from Vienna at the gate
16:45BA 635 to London Heathrow leaves the gate
18 h 50 apart on the timetable, overnight
BA 635 leaves 18 h 50 after GQ 841 arrives on the timetable: more than half a day, so not a connection we count.