BA 783 then A3 609 at Heathrow
Stockholm → London → Athens
Timetable, London time
22:20BA 783 from Stockholm at the gate
22:15A3 609 to Athens leaves the gate
23 h 55 apart on the timetable, overnight
A3 609 leaves 23 h 55 after BA 783 arrives on the timetable: more than half a day, so not a connection we count.