BA 419 then A3 609 at Heathrow
Luxembourg → London → Athens
Timetable, London time
09:55BA 419 from Luxembourg at the gate
22:15A3 609 to Athens leaves the gate
12 h 20 apart on the timetable
A3 609 leaves 12 h 20 after BA 419 arrives on the timetable: more than half a day, so not a connection we count.