BA 1399 then BA 1354 at Heathrow
Belfast City → London → Saint Helier
Timetable, London time
16:35BA 1399 from Belfast City at the gate
16:20BA 1354 to Saint Helier leaves the gate
23 h 45 apart on the timetable, overnight
BA 1354 leaves 23 h 45 after BA 1399 arrives on the timetable: more than half a day, so not a connection we count.