BA 1391 then BA 932 at Heathrow
Belfast City → London → Düsseldorf
Timetable, London time
10:05BA 1391 from Belfast City at the gate
09:15BA 932 to Düsseldorf leaves the gate
23 h 10 apart on the timetable, overnight
BA 932 leaves 23 h 10 after BA 1391 arrives on the timetable: more than half a day, so not a connection we count.