BA 931 then BA 678 at Heathrow
Düsseldorf → London → Istanbul
Timetable, London time
10:50BA 931 from Düsseldorf at the gate
10:35BA 678 to Istanbul leaves the gate
23 h 45 apart on the timetable, overnight
BA 678 leaves 23 h 45 after BA 931 arrives on the timetable: more than half a day, so not a connection we count.