BA 1399 then BA 574 at Heathrow
Belfast City → London → Milan Linate
Timetable, London time
16:10BA 1399 from Belfast City at the gate
14:40BA 574 to Milan Linate leaves the gate
22 h 30 apart on the timetable, overnight
BA 574 leaves 22 h 30 after BA 1399 arrives on the timetable: more than half a day, so not a connection we count.