BA 961 then A3 601 at Heathrow
Hamburg → London → Athens
Timetable, London time
12:20BA 961 from Hamburg at the gate
12:15A3 601 to Athens leaves the gate
23 h 55 apart on the timetable, overnight
A3 601 leaves 23 h 55 after BA 961 arrives on the timetable: more than half a day, so not a connection we count.