BA 551 then BA 209 at Heathrow
Rome → London → Miami
Timetable, London time
15:05BA 551 from Rome at the gate
14:30BA 209 to Miami leaves the gate
23 h 25 apart on the timetable, overnight
BA 209 leaves 23 h 25 after BA 551 arrives on the timetable: more than half a day, so not a connection we count.