BA 679 then A3 609 at Heathrow
Istanbul → London → Athens
Timetable, London time
22:35BA 679 from Istanbul at the gate
22:15A3 609 to Athens leaves the gate
23 h 40 apart on the timetable, overnight
A3 609 leaves 23 h 40 after BA 679 arrives on the timetable: more than half a day, so not a connection we count.