BA 873 then BA 1406 at Heathrow
Krakow → London → Belfast City
Timetable, London time
18:05BA 873 from Krakow at the gate
17:10BA 1406 to Belfast City leaves the gate
23 h 05 apart on the timetable, overnight
BA 1406 leaves 23 h 05 after BA 873 arrives on the timetable: more than half a day, so not a connection we count.